Kerala SCERT · Standard IX

Class 9 Physics — Onam Exam 2026

Kerala SCERT · First Terminal · Mon 17 Aug 2026, afternoon · 40 marks / 1½ hrs

Exam dates vary by school and sources disagree — confirm your own timetable.

Made by [thenvis] · last updated 16 Aug 2026

Straight talk first. Nobody — not Xylem, not Eduport, not Exam Winner, not this guide — has the actual 2026 paper. Kerala first-term papers are set at district/school level and are not leaked in advance. What follows is a probability map built from the textbook, the SCERT model papers, and past first-term papers. "100% sure question" videos are marketing language for "very high frequency topic." Treat the ★★★ items as near-certain topics, not near-certain wordings.

Chemistry — and this time it's from a real paper

Everything in this section is checked against papers the government actually set. For Chemistry there is one: a real Pareeksha Bhavan "Summative Assessment — Term 1, 2025-26" Class 9 Chemistry paper, archived on Education Observer. All 18 questions were extracted, and every Chemistry question here is modelled on what that paper actually asked.

What that real paper examined

Chapter	Share of the real paper	Verdict
1. Structure of Atom	about 9 of 18 questions	Core
2. Periodic Table	about 7 of 18 questions	Core
3. Chemical Bonding	2 questions, and both were really electron-configuration questions in disguise (CaO, ionic formation)	Light
4. Redox Reactions	zero — no oxidation numbers, no oxidising/reducing agents, no balancing	Did not appear
5–8 (Part 2)	none	No

One caveat, stated plainly. The generic SCERT-style model paper that circulates online is heavy on Chapter 3 and Chapter 4 — electron-dot diagrams, oxidation numbers, balancing equations. So Redox clearly can be asked. It just wasn't, in the one real first-term paper available. Treat Chapters 1 and 2 as the near-certain core, give Chapter 3 a light pass focused on ionic-compound formation, and check your own notebook before deciding whether to touch Redox.

The Chemistry paper is a different shape from Physics

This one is easy to miss and it matters. The real Chemistry paper does not use the "answer any 3 of 4" structure the Physics model papers use. It runs:

Section	Structure	Total
I	Q1–4, answer all, 1 score each	4
II	Q5–11, answer all (2 of them carry an internal OR), 2 scores each	14
III	Q12–17, answer all (2 carry an internal OR), 3 scores each	18
IV	Q18 only, with one OR, 4 scores	4

What this changes for you: in Physics you can skip your weakest five questions. In Chemistry you cannot skip anything — every question must be attempted, and the only choice is between two alternatives inside a handful of them. So there is no hiding a weak topic. Budget your time evenly across all 18.

Highest-probability Chemistry topics, straight from that paper: electron configuration from atomic number · group and period from configuration · protons/neutrons/electrons from Z and A · ion-formation equations · atomic size trends with reasons · scientist-to-model matching · isotopes and isobars with uses · noble-gas configuration matching · transition elements and the penultimate shell · Rutherford's three postulates.

Biology — same shape as Chemistry, and a date you must check

Evidence: the genuine SCERT Model Question Paper, First Term 2025-26 (full question text), plus real Pareeksha Bhavan answer keys for 2024-25 and 2025-26 confirming structure and topics.

The paper

40 marks, 18 questions, 1½ hours + 15 minutes reading. Bands: 4×1 + 7×2 + 6×3 + 1×4. Every question compulsory, with either/or inside about five of them — structurally identical to the Chemistry paper. That cross-subject match is itself good evidence that this is the standard current format for Class 9 science papers.

Which chapters appeared

Chapter	Evidence
1 · To Life Processes	Core diffusion, osmosis, facilitated diffusion, active transport, plasmolysis, photosynthesis light and dark phases, chloroplast structure, metabolism, homeostasis
2 · Digestion and Transport of Nutrients	Core Amoeba vs Hydra, tooth structure, villi, epiglottis, bile and the liver, blood, heart, cardiac cycle, circulation
3 · Respiration and Excretion	Did not appear in any of the three documents — no lungs, no alveoli, no nephron
4–6 (Behind Movements, Reproductive Health, Classification)	Part 2 — not in the portion

On Chapter 3: it is nominally in the Part 1 portion but absent from every real and model paper checked — the same pattern as Redox in Chemistry. Learn the headline facts (nephron, glomerulus, Bowman's capsule, urea, alveoli, stomata, lenticels) so you could attempt a question, but don't let it eat into Chapters 1 and 2.

The date is genuinely unresolved

Two timetable sites disagree, and not just about Biology — they disagree about the whole week. careers360 puts Biology on Wed 19 Aug, afternoon; schools360 puts it on Thu 20 Aug, afternoon. The two agree only that Social Science is on the 19th forenoon. More web searching will not settle this — check your school's own notice.

Social Science — two real years of evidence

The strongest evidence base of all five subjects. Three documents were used — the real Summative Assessment Term I 2025-26 answer key, the real 2024-25 answer key, and the SCERT model paper — and all three agree on structure and on which chapters get examined.

The paper

Wed 19 Aug 2026, 10:00–12:45. One combined 80-mark paper (History, Civics, Geography and Economics together — not split into Social Science I and II). 30 questions, 2½ hours plus 15 minutes reading time. Mark bands: Q1–8 × 1 · Q9–13 × 2 · Q14–21 × 3 · Q22–28 × 4 · Q29–30 × 5.

Every question is compulsory, exactly like Chemistry. The only choice is an either/or inside about six of the 3, 4 and 5-mark questions. Notice where the marks actually are: the 3, 4 and 5-mark bands carry 62 of the 80 marks. Those are all "explain / describe / justify" questions — so reasoning, not recall, is what this paper rewards.

Which chapters actually appeared

Chapter	Evidence
Ideas and Early States	Heaviest Arthashastra, Saptanga, Magadha, Mauryas, Ashoka's Dhamma, Buddhism, Jainism, Athenian democracy
On the Roof of the World	Heaviest the three ranges, Bugyals, Karewas, river origins, climate, tourism phases, map-marking
Moving Forward from the Stone Age	Strong tools by age, Neolithic Revolution, Harappan urbanisation
In the Expansive Plain	Strong Bhabar, Tarai, Bhangar, Khadar, alluvial fans, doabs
Distribution of Power	Strong the three lists, Lok Sabha, federalism, separation of powers
Human Resources for National Development	Strong factors of production, human capital, unemployment, poverty
Land Grants and the Indian Society	Did not appear in either real year
Demographic Trends in India	Did not appear in either real year
Plateau Where the Earth's History Slumbers	Did not appear in either real year

The caveat on those last three: two years is not many, and Kerala first-terminals are set at school or district level. They may simply be taught after the Onam cutoff. Treat them as low priority rather than zero risk, and check your own notebook.

One factual correction worth having: the Lok Sabha has 543 members. Some notes online say 550 — that is the constitutional maximum, not the actual strength. The real answer key uses 543.

English — what is and isn't confirmed

Worth being upfront about this one, because guessing here would do real damage.

Not confirmed: the exact unit and lesson list of the current Class 9 English coursebook. Search results point to lessons called The Race, Learning the Game, Bang the Drum and Maternity — but there is also a new SCERT Class 9 English textbook dated 2024, and it is unclear whether those titles belong to the new book or the old one. The paper's total marks and section structure are also unconfirmed. Practice questions about the wrong lessons would be worse than useless, so none are included.

What is here instead — the parts of a Kerala English paper that are the same whatever your textbook says, and which carry most of the marks:

Discourse writing — diary entry, letter, notice, conversation, character sketch, speech, narrative. Format is roughly half the marks on these and is pure memorisation. Learn the skeletons.
Language elements — question tags, reported speech, editing for errors, prepositions, phrasal verbs, connectors, verb forms, active/passive. All mechanical, all repeatable.
Comprehension technique — the unseen passage needs no memorisation at all, which makes it the most reliable source of marks in the whole paper.

What to do: open the English notebook and check which units the class actually finished, then revise those lessons — characters, themes, key events — alongside the discourse and grammar practice here. Once the unit list is confirmed, lesson-specific questions can be added.

1 · What's actually in the Physics portion

The Class 9 Physics book (new SCERT textbook, 8 chapters) splits into Part 1 = Ch 1–4, Part 2 = Ch 5–8. First term covers what was taught June → July, and the exam is only 40 marks in 1½ hours.

Chapter	In the Onam paper?	Expected weight
1. Refraction of Light	Certain	~14–18 marks
2. Equations of Motion	Certain	~14–18 marks
3. Laws of Motion	Possible — if your teacher finished it	0–8 marks
4. Gravitation	Unlikely	0
5–8 (Buoyancy, Work & Energy, Electricity, Sound)	No	0

Action: check your own class notebook. If Laws of Motion was started and momentum (p = mv) was taught, do the Ch 3 questions in the quiz too — they are tagged separately. If not, ignore them and put that time into refraction numericals.

2 · Paper pattern (this is the reliable part)

Every SCERT Class 9 Physics model paper follows the same skeleton, and first-term papers copy it:

Section	Format	Total	What it tests
I	Answer 3 of 4 · 1 mark	3	One-word / MCQ / odd-one-out. Definitions and units.
II	Answer 7 of 9 · 2 marks	14	Short reason, one-step numerical, match the following.
III	Answer 5 of 6 · 3 marks	15	Two-step numericals, explain-with-diagram.
IV	Answer 2 of 3 · 4 marks	8	Long: derivation, graph, multi-part numerical.

The choice matters more than people realise. You skip 1 in Section I, 2 in II, 1 in III, 1 in IV. So there is room to drop your weakest topic entirely. But you cannot drop a whole chapter — both chapters appear in every section.

Cool-off time: 15 minutes before writing. Use it to mark which questions you'll skip, and to write the three motion equations on the rough side of the answer sheet before you forget them.

3 · Highest-probability question types, with reasoning

Chapter 1 — Refraction of Light

Question type	Odds	Why it comes
Calculate speed of light in a medium from n, or n from speed	★★★	Only formula in the chapter that gives a clean one-step numerical. Perfect 2-mark question. Appears in almost every model paper.
Explain a real-life phenomenon (mirage / twinkling stars / early sunrise / pool looks shallow / bent pencil)	★★★	The new textbook is written around real-life applications. Examiners love these because they separate memorisers from understanders. Expect one 2-mark and one 3-mark.
Total internal reflection: two conditions + critical angle	★★★	The single most "examinable" definition in the chapter, and it links to optical fibre + diamond sparkle. Frequently the 4-mark question.
Laws of refraction / bends toward or away from normal	★★★	Guaranteed somewhere — usually a 1-mark fill-in or part of a 2-mark.
Snell's law numerical (find angle or index)	★★	Comes up when the paper-setter wants a harder 3-mark. Needs sin values, so some setters avoid it at Class 9.
Refractive index table comparison (which is denser / where is light slowest)	★★	Easy 1–2 mark, tests whether you understand n is a ratio, not a speed.
What changes and what stays the same during refraction (speed, wavelength, frequency)	★★	Classic trick question. Frequency does not change — high chance as a 1-mark or MCQ distractor.
Ray diagram: glass slab / lateral shift	★★	Diagram questions are cheap to mark. Often 3-mark "draw and label".

Chapter 2 — Equations of Motion

Question type	Odds	Why it comes
Numerical using v = u + at or s = ut + ½at²	★★★	The bread and butter of this chapter. There will be at least two, almost certainly three.
Distance vs displacement (definition or a circular-track problem)	★★★	The conceptual anchor of the chapter. Circular track / return-to-start problems where displacement = 0 are an examiner favourite because students auto-pilot and answer with distance.
Velocity–time graph: find acceleration and displacement (area under graph)	★★★	Graph questions carry 3–4 marks and are easy to set. "Area under v–t graph = displacement" is the exact fact they test.
Free fall / stone thrown upward (max height, time to return)	★★★	Directly worked in the textbook. Setters lift these with numbers changed. Watch the sign of g and that v = 0 at the top.
Braking / deceleration numerical using v² = u² + 2as	★★	Ties to the road-safety theme the chapter is built on. Good 3-mark.
Scalar vs vector classification	★★	Cheap 1-mark. Know: distance, speed, time, mass = scalar; displacement, velocity, acceleration, force = vector.
Uniform vs non-uniform motion / interpret a distance–time graph shape	★★	Usually 1–2 marks. Straight line = uniform, curve = non-uniform.
Derive one of the three equations (graphically)	★	Possible as the 4-mark, but Class 9 setters more often ask for the graph interpretation instead of the derivation.

Chapter 3 — Laws of Motion (only if taught)

Question type	Odds	Why it comes
State Newton's laws / examples of inertia	★★	If the chapter is in portion, this is the guaranteed easy question.
Momentum calculation p = mv, or force from change in momentum	★★	The only numerical if only the first half of the chapter was covered.
Why a cricketer pulls hands back while catching	★★	The textbook's signature example. Impulse reasoning, 2–3 marks.

4 · Background check on the channels

You asked how likely these channels are to actually guess the questions. Here's an honest read.

Channel	What it is	How much to trust the "sure questions"
Xylem Learning	Kozhikode-based edtech founded 2020 by Ananthu S Kumar, bootstrapped, ~1,300+ staff. Core business is NEET/JEE; Kerala state-syllabus school classes are a large free-YouTube funnel into paid courses.	Medium-high on topics, low on exact questions. Big faculty team means their topic selection is well-informed. But the school-syllabus content is a marketing channel — "100% sure" framing is designed to get the click.
Eduport	Calicut-based, founded by Ajas, literally started as a YouTube channel before becoming an app. 600K+ app downloads, 50+ instructors, dedicated Class 7/8/9/SSLC streams. Publishes answer-key discussion videos right after each Onam paper.	Medium-high. The fact that they post answer keys within hours means they systematically collect real papers — so their pattern knowledge is genuinely good. Their post-exam accuracy is verifiable; their pre-exam predictions are not.
Exam Winner	Separate Class 9 / SSLC channels, chapter-wise "one-shot" videos with named faculty (Dilsha for most Class 9 physics chapters). Heavy on "Most Important Questions" / "100% Sure Questions" titling.	Medium. Their one-shot videos are solid revision. The "sure question" videos are essentially a filtered list of textbook + model-paper questions — useful, but the title overpromises.
PW (Physics Wallah) Kerala	The Kerala arm of Physics Wallah — founded 2016 by Alakh Pandey as a YouTube channel, now a listed company (IPO Nov 2025, ~$2.8B valuation before it). In Kerala it runs PW Kerala SSLC and PW Kerala Plus 2 & KEAM.	PW's better-known Kerala channels — @PWKeralaSSLC and @PWKeralaPlusTwoKEAM — cover Class 10 and Plus Two only. There is a separate Class 9 channel (see the row below). The real risk is landing on Class 9 CBSE content (PW Foundation) by mistake: that is a different textbook entirely, with no "Refraction of Light" chapter and a different motion sequence.
"Major Exam Online"	No channel by this exact name could be confirmed in the Kerala Class 9 space. It may be Exam Winner under another name, or a smaller regional channel that doesn't surface in search.	Unverified. Worth checking directly in the YouTube app if a classmate uses it.

The honest verdict

Their topic prediction is genuinely good — maybe 80–90% of the topics they flag will appear in some form. That's not clairvoyance; a 40-mark paper on two chapters has a limited number of things it can ask.
Their exact-question prediction is weak — realistically 10–30% of specific wordings match. And Kerala first-term papers vary by district, so a channel can't hit all of them.
The real value is the filtering, not the prophecy. They tell you which 20 things out of 60 to revise. That's worth watching.
Watch out for: videos recycled from previous years (check the upload date), and predictions based on the old syllabus. The textbook changed — if a video mentions chapters that aren't in your book, close it.

5 · Two-day plan (you have ~48 hours)

Today: Do the quiz on this page end to end. Every question you miss, mark the chapter and reread that textbook page — not a video, the actual page.
Tonight: Write out from memory: the 3 equations of motion, n = c/v, sin C = 1/n, and the two conditions for TIR. If you can't do it blind, you don't know it yet.
Tomorrow morning: Solve last year's Class 9 first-term physics paper under timer (search "Kerala Class 9 first term physics question paper 2025" — Education Observer and AglaSem both host it free).
Tomorrow evening: One channel revision video at 1.5× speed, just to catch anything you missed. Then stop. Do not start Gravitation.
Exam day: In the 15-min cool-off, write the formulas on the rough page first. Then pick your skips.

Why I made this

Every channel says something different about what's coming, and half the "100% sure question" videos turn out to be recycled from last year. So instead of guessing, I went and found the actual papers — real Pareeksha Bhavan first-term papers from 2024-25 and 2025-26, plus the SCERT model papers — and built the questions from what was really asked. Every source is listed in the Sources tab if you want to check for yourself.

Pick a subject above. Cards for quick revision, Learn if you want to actually understand something, Mock Paper when you're ready to sit one under a clock.

Good luck — and send this to anyone else writing the same exam.

Written to the exact SCERT Class 9 Physics first-terminal skeleton for 2026–27: 40 marks, 1½ hours, four sections with internal choice. Sit it under timer with a clock in front of you. Answers are hidden until you click — don't cheat yourself.

FIRST TERMINAL EVALUATION 2026–27

STANDARD IX · PHYSICS

Time: 1½ HoursTotal Score: 40

General instructions: 15 minutes cool-off time. Read the questions carefully. Answer only the required number of questions from each section. Take g = 10 m/s² and speed of light in vacuum c = 3 × 10⁸ m/s wherever needed.

SECTION IAnswer any 3 questions. 1 score each. (3 × 1 = 3)

1. When light travels from air into glass, which of these remains unchanged? (a) speed (b) wavelength (c) frequency (d) direction

(c) frequency. Frequency is fixed by the source of light. Speed and wavelength both decrease on entering glass, and the ray changes direction because it enters obliquely.

2. The area under a velocity–time graph gives the __________ of the body.

Displacement (distance travelled).

3. Find the odd one out: distance, speed, time, velocity.

Velocity — it is the only vector quantity in the list. Distance, speed and time are all scalars.

4. The refractive index of diamond is 2.42, and that of water is 1.33. In which medium does light travel faster?

Water. Since v = c/n, a smaller refractive index means a greater speed of light in the medium.

SECTION IIAnswer any 7 questions. 2 scores each. (7 × 2 = 14)

5. The refractive index of water is 1.33. Calculate the speed of light in water.

n = c/v, so v = c/n = (3 × 10⁸) / 1.33 = 2.26 × 10⁸ m/s
Marking: 1 for writing the correct formula, 1 for the answer with unit.

6. Write any two differences between distance and displacement.

(i) Distance is the total length of the path covered; displacement is the shortest straight-line distance between the initial and final positions.
(ii) Distance is a scalar; displacement is a vector.
(iii) Distance can never be zero for a body in motion, but displacement can be zero if the body returns to its starting point.

7. We can see the Sun about two minutes before it actually rises above the horizon. Give the reason.

This is due to atmospheric refraction. The optical density of the atmosphere increases towards the Earth's surface, so sunlight entering it bends continuously towards the normal. As a result the Sun appears to be at a position higher than its actual position, and becomes visible before it has actually risen.

8. A car starting from rest attains a velocity of 20 m/s in 8 seconds. Calculate its acceleration.

u = 0, v = 20 m/s, t = 8 s
v = u + at → 20 = 0 + a(8) → a = 20/8 = 2.5 m/s²

9. Match the phenomenon in Column A with its cause in Column B.

Column A	Column B
(i) Mirage	(a) Refraction at the air–water surface
(ii) Twinkling of stars	(b) Total internal reflection inside a fibre
(iii) Optical fibre	(c) Total internal reflection in hot air layers
(iv) A pencil in water looks bent	(d) Continuously changing atmospheric refraction

(i) – (c), (ii) – (d), (iii) – (b), (iv) – (a)

10. Define critical angle. Write the relation connecting critical angle and refractive index.

The critical angle is the angle of incidence in the optically denser medium for which the angle of refraction in the rarer medium becomes 90°.
Relation: sin C = 1/n (where n is the refractive index of the denser medium with respect to the rarer one).

11. A body moves along a circular path with constant speed. Its velocity, however, is not constant. Why?

Velocity is a vector, so it depends on both magnitude and direction. On a circular path the direction of motion changes continuously, even though the magnitude (speed) stays the same. So the velocity keeps changing, which means the body is accelerating.

12. A stone is dropped from a height of 20 m. How long does it take to reach the ground? Take g = 10 m/s²

"Dropped" means u = 0, and a = g = 10 m/s².
s = ut + ½at² → 20 = 0 + ½(10)t² = 5t²
t² = 4 → t = 2 s

13. State the two laws of refraction of light.

First law: The incident ray, the refracted ray and the normal drawn at the point of incidence all lie in the same plane.
Second law (Snell's law): For a given pair of media, the ratio sin i / sin r is a constant. This constant is the refractive index of the second medium with respect to the first.

SECTION IIIAnswer any 5 questions. 3 scores each. (5 × 3 = 15)

14. A ball is thrown vertically upward with a velocity of 30 m/s. (a) Find the maximum height it reaches. (b) Find the time taken to reach the maximum height. (c) What is its total time of flight? Take g = 10 m/s²

At the highest point the ball momentarily stops, so v = 0. Taking upward as positive, a = −g = −10 m/s².
(a) v² = u² + 2as → 0 = 30² − 2(10)h → 900 = 20h → h = 45 m
(b) v = u + at → 0 = 30 − 10t → t = 3 s
(c) The time to come down equals the time to go up, so total time of flight = 6 s

15. Explain, with reasons, how a mirage is formed on a tarred road on a hot summer day.

• On a hot day the air layer just above the road is strongly heated, so it becomes optically rarer than the cooler air above it.
• Light coming from the sky therefore travels from denser layers into rarer layers and bends away from the normal at each layer, so the ray gradually curves.
• At one of these layers the angle of incidence becomes greater than the critical angle, and the light undergoes total internal reflection.
• This reflected light reaches the observer's eye from below, forming an inverted image of the sky that looks like a pool of water on the road.

16. A bus travelling at 25 m/s is brought to rest over a distance of 62.5 m by applying brakes. (a) Calculate its retardation. (b) How long does it take to stop?

u = 25 m/s, v = 0, s = 62.5 m
(a) v² = u² + 2as → 0 = 625 + 2a(62.5) → 125a = −625 → a = −5 m/s².
The negative sign shows it is retardation, so the retardation is 5 m/s².
(b) v = u + at → 0 = 25 + (−5)t → t = 5 s

17. Draw a ray diagram showing the path of a ray of light passing obliquely through a rectangular glass slab. Mark the lateral shift and explain why the emergent ray is parallel to the incident ray.

Diagram: Draw the slab as a rectangle. Show the incident ray striking the top surface obliquely, the normal at that point, the refracted ray bending towards the normal inside the glass, then the emergent ray at the bottom surface bending away from the normal. Draw a dotted extension of the original incident ray — the perpendicular gap between that dotted line and the emergent ray is the lateral shift.

Explanation: The light bends towards the normal on entering (air → glass, rarer to denser) and by exactly the same amount away from the normal on leaving (glass → air, denser to rarer), because the two surfaces are parallel. The two deviations cancel, so the emergent ray is parallel to the incident ray — only shifted sideways.

18. The refractive index of a certain glass is 1.5. (a) Find the speed of light inside this glass. (b) State the two conditions needed for total internal reflection.

(a) v = c/n = (3 × 10⁸)/1.5 = 2 × 10⁸ m/s
(b) (i) Light must travel from an optically denser medium to an optically rarer medium.
(ii) The angle of incidence must be greater than the critical angle of that pair of media.

19. Why does a cut diamond sparkle brilliantly? Name one more device that works on the same principle and state one of its uses.

Diamond has a very high refractive index (2.42), so its critical angle is very small — about 24°. Light entering the diamond strikes the inner faces at angles greater than this almost every time, so it undergoes repeated total internal reflection inside the stone before emerging through the top. This concentrated light is seen as sparkle, and the cut of the stone is designed to encourage it.

Another device: the optical fibre, which also works on total internal reflection. Uses: telecommunication and internet data transmission, and endoscopy in medicine.

SECTION IVAnswer any 2 questions. 4 scores each. (2 × 4 = 8)

20. An object starts from rest and moves with a uniform acceleration of 4 m/s². (a) Find its velocity at the end of 5 seconds. (b) Find the distance travelled in those 5 seconds. (c) Find the distance travelled during the 5th second alone. (d) What is the shape of its velocity–time graph?

u = 0, a = 4 m/s²
(a) v = u + at = 0 + 4(5) = 20 m/s
(b) s = ut + ½at² = 0 + ½(4)(5²) = 2 × 25 = 50 m
(c) Distance in the 5th second = (distance in 5 s) − (distance in 4 s)
= 50 − [½(4)(4²)] = 50 − 32 = 18 m
(Or directly: s_n = u + ½a(2n−1) = 0 + ½(4)(9) = 18 m)
(d) A straight line passing through the origin, sloping upward — because the velocity increases uniformly with time. Its slope gives the acceleration, 4 m/s².

21. The velocity–time graph of a body is shown below. (a) Describe the motion of the body in each of the three parts. (b) Calculate the acceleration during the first 4 seconds. (c) Calculate the total displacement of the body.

(a) 0–4 s: velocity increases uniformly from 0 to 20 m/s — uniform acceleration.
4–10 s: velocity stays at 20 m/s — uniform velocity, zero acceleration.
10–12 s: velocity falls uniformly from 20 m/s to 0 — uniform retardation.
(b) Acceleration = slope = (20 − 0)/(4 − 0) = 5 m/s²
(c) Displacement = area under the graph = area of triangle + rectangle + triangle
= ½(4)(20) + (6)(20) + ½(2)(20)
= 40 + 120 + 20 = 180 m

22. (a) What is meant by total internal reflection?
(b) A medium has a refractive index of 2. Calculate its critical angle. (sin 30° = 0.5) (c) Explain why stars appear to twinkle while planets do not.

(a) When a ray of light travelling in an optically denser medium strikes the surface of a rarer medium at an angle of incidence greater than the critical angle, the ray is not refracted at all — it is reflected back completely into the denser medium. This is total internal reflection.
(b) sin C = 1/n = 1/2 = 0.5, therefore C = 30°
(c) Starlight passes through atmospheric layers whose optical density keeps changing, so it is refracted by continuously varying amounts. Since a star is extremely far away it behaves as a point source, so these variations make its apparent brightness and position flicker — it twinkles. A planet is far closer and behaves as a collection of many point sources; the variations from different points average out, so a planet shines steadily.

End of question paperTotal: 3 + 14 + 15 + 8 = 40 scores

This one is built on a real paper. The structure below is copied from the actual Pareeksha Bhavan "Summative Assessment — Term 1, 2025-26" Class 9 Chemistry paper: 18 questions, 40 marks, 1½ hours. Note it is not the "answer any 3 of 4" style the Physics paper uses — here you answer every question, and the choice is an OR inside a few of them.

FIRST TERMINAL EVALUATION 2026–27

STANDARD IX · CHEMISTRY

Time: 1½ HoursTotal Score: 40

Instructions: 15 minutes cool-off time. Answer all questions. Some questions carry an internal choice — attempt only one of the alternatives in those.

SECTION IAnswer all questions from 1 to 4. 1 score each. (4 × 1 = 4)

1. Find the relation and fill in suitably.Planetary model : Rutherford :: Plum pudding model : __________

J. J. Thomson.

2. Mainly, the mass of an atom depends on the mass of __________. (a) protons and electrons (b) electrons and neutrons (c) protons and neutrons (d) neutrons and electrons

(c) protons and neutrons. An electron's mass is only about 1/1836 of a proton's, so it contributes almost nothing.

3. In which group of the modern periodic table are the noble gases placed?

Group 18.

4. Match the following.

A	B
(i) Neils Bohr	(a) Gold foil experiment
(ii) William Crookes	(b) Stationary energy levels
(iii) Rutherford	(c) Discharge tube experiment

(i) – (b), (ii) – (c), (iii) – (a)
The real paper included "neutron" as a fourth option — that belongs to Chadwick, not to any of these three.

SECTION IIAnswer all questions from 5 to 11. 2 scores each. (7 × 2 = 14)

5. Magnesium is an alkaline earth metal (atomic number 12). (a) How is the magnesium ion formed? (b) Write the chemical equation for its formation.

(a) Magnesium's configuration is 2,8,2. It loses its two valence electrons to attain the stable neon configuration (2,8).
(b) Mg → Mg²⁺ + 2e⁻

6. The configurations of four elements are: A = 2,8,2 B = 2,4 C = 2,8,4 D = 2,8,3. (a) Which two belong to the same group? (b) Which belong to the same period?

(a) B and C — both have 4 valence electrons, so both are in Group 14.
(b) A, C and D — all have 3 shells, so all are in Period 3.

7. Complete the table of isotope uses.

Isotope	Use
Cobalt-60	__________
__________	Diagnosis of anaemia

Cobalt-60 → treatment of cancer. Iron-59 → diagnosis of anaemia.
Also worth knowing: Carbon-14 for dating fossils, Iodine-131 for thyroid disorders, Uranium-235 as nuclear fuel.

8. (Either) Using the discharge tube experiment, write any two properties of cathode rays. (Or) Write any two differences between Thomson's model and Rutherford's model of the atom.

Either: Cathode rays travel in straight lines from the cathode to the anode; they are made of negatively charged particles (electrons) — they are deflected towards the positive plate in an electric field; they have mass, since they can rotate a light paddle wheel placed in their path.

Or: Thomson pictured positive charge spread evenly through the atom with electrons embedded in it; Rutherford concentrated all the positive charge and nearly all the mass in a tiny nucleus. Thomson's atom had no empty space; Rutherford showed the atom is mostly empty space with electrons revolving around the nucleus.

9. Element X has 3 electron shells and 6 valence electrons. Write its electron configuration and identify its element family.

Configuration: 2,8,6 (atomic number 16 — sulphur). Group = 6 + 10 = 16, so it belongs to the oxygen family.

10. Two atoms are represented as ₁₈X⁴⁰ and ₂₀Y⁴⁰. Are they isotopes or isobars? Justify your answer.

They are isobars. Their atomic numbers differ (18 and 20), so they are different elements, but their mass numbers are the same (both 40). Isotopes would be the reverse — same atomic number, different mass number.

11. Element Q lies in the 3rd period and the 13th group. (a) Write its electron configuration. (b) Identify the element.

(a) Period 3 → 3 shells. Group 13 → valence electrons = 13 − 10 = 3. Configuration: 2,8,3
(b) Atomic number 13 — aluminium (Al).

SECTION IIIAnswer all questions from 12 to 17. 3 scores each. (6 × 3 = 18)

12. Write any three main postulates of Rutherford's model of the atom.

(1) Most of an atom is empty space.
(2) The whole positive charge and almost the entire mass are concentrated in a very small central region called the nucleus.
(3) Electrons revolve around the nucleus in circular paths, which is why it is called the planetary model.

13. In scandium the last electron enters the penultimate shell, and its configuration is 2,8,9,2. (a) Write the configuration of the element just before scandium. (b) Which group does that element belong to? (c) What are elements like scandium called?

(a) 2,8,8,2 — calcium, atomic number 20.
(b) 2 valence electrons → Group 2 (alkaline earth metals).
(c) Transition elements, because the last electron enters the penultimate shell rather than the outermost one.

14. (Either) (a) Why do transition elements show similarity within a group and across a period? (b) Give two transition elements used in daily life. (Or) (a) In which groups are the main-group elements found? (b) Give one main-group element that is solid at room temperature and one that is liquid.

Either: (a) In transition elements the last electron enters the penultimate shell, so the number of outermost electrons stays the same across the series — that is why properties are similar both down a group and across a period. (b) Iron and copper (also zinc, silver, gold).

Or: (a) Main-group elements are in Groups 1, 2 and 13–18. (b) Solid: sodium (or magnesium, aluminium, carbon). Liquid at room temperature: bromine (mercury is a transition element, so it does not qualify here).

15. Three elements have atomic numbers A = 12, B = 15, C = 17. (a) Arrange them in increasing order of atomic size. (b) Justify your answer. (c) How does atomic size change down a group? Give the reason.

(a) C < B < A (that is, 17 < 15 < 12 in size order).
(b) All three are in Period 3. Across a period the number of shells stays the same but the nuclear charge increases, pulling the electrons closer, so size decreases left to right.
(c) Down a group atomic size increases, because a new shell is added at each step and the outermost electrons lie further from the nucleus.

16. CaO is an ionic compound. The atomic number of calcium is 20 and of oxygen is 8. (a) Write the chemical equation for the formation of the oxide ion. (b) Name the noble gas having the same configuration as the oxide ion. (c) How many electrons and protons are present in the calcium ion?

(a) O + 2e⁻ → O²⁻
(b) The oxide ion is 2,8 — the same as neon.
(c) Ca²⁺ has lost 2 electrons, so it has 18 electrons and still 20 protons.

17. (Either) The atomic number of an element is 16. (a) In how many shells are its electrons distributed? (b) Which of these shells has the highest energy? Give the reason. (Or) The atomic number of an element is 15. (a) Which is its valence shell? (b) Which shell has the least energy? Give the reason.

Either: Configuration 2,8,6. (a) Three shells (K, L, M). (b) The M shell has the highest energy, because energy increases with distance from the nucleus — the further a shell is, the weaker the nuclear attraction and the higher its energy.

Or: Configuration 2,8,5. (a) The valence shell is the M shell (the outermost). (b) The K shell has the least energy, because it is closest to the nucleus and most strongly attracted.

SECTION IVQuestion 18 carries an internal choice. 4 scores. (1 × 4 = 4)

18. (Either) Elements X, Y and Z are described below (symbols are not real). X — in the 3rd period, needs 1 more electron to complete its octet. Y — in the 4th period, not a transition element, its highest-energy shell has 1 electron. Z — in the 1st period, has the same number of valence electrons as Y. (a) Write the electron configurations of X and Y. (b) Identify Z. (c) Which isotope of Z has no neutron?

(a) X = 2,8,7 (chlorine, atomic number 17 — it needs one electron for the octet).
Y = 2,8,8,1 (potassium, atomic number 19 — 4 shells, 1 valence electron, not a transition element).
(b) Z is in Period 1 with 1 valence electron → hydrogen.
(c) Protium (¹H), the ordinary hydrogen isotope, has one proton and no neutron.

End of question paperTotal: 4 + 14 + 18 + 4 = 40 scores

Read this before you start. The exact section structure and lesson list for Class 9 English could not be confirmed, so this is a practice paper on the parts of a Kerala English paper that do not change: comprehension technique, discourse writing and language elements. Those carry most of the marks in any version of the paper. Add lesson-based revision on top of this — check the notebook for which units the class finished.

FIRST TERMINAL EVALUATION 2026–27

STANDARD IX · ENGLISH · practice paper

Suggested time: 2 hoursPractice total: 40

SECTION AReading & comprehension

1. Read the passage and answer the questions. Kochi's backwaters once carried more cargo than its roads. Country boats moved rice, coir and spices between the villages long before the first lorry arrived. Today most of that traffic has gone, and the canals that carried it are choked with weed. A group of students from a school in Ernakulam decided that this was not inevitable. Over eight weekends they cleared a two-kilometre stretch of one canal, planted its banks, and persuaded the local council to install three waste screens. The canal is not what it was a century ago. But water moves through it again, and last month a kingfisher was seen there for the first time in years. (a) What did the backwaters of Kochi carry in the past? (1) (b) Why did the canal traffic disappear? (1) (c) What three things did the students do? (2) (d) Why does the writer mention the kingfisher at the end? (2)

(a) They carried cargo — rice, coir and spices — between the villages in country boats.
(b) Because roads and lorries took over the transport of goods, so the canals fell out of use and became choked with weed.
(c) They cleared a two-kilometre stretch of the canal, planted its banks, and persuaded the local council to install three waste screens.
(d) The kingfisher is evidence that the canal is alive again. The writer uses it to show that the students' work had a real, visible result — that damage to a waterway is not permanent and can be reversed by ordinary people.
Technique: notice how each answer's length matches its marks — one sentence for 1 mark, two or three points for 2.

SECTION BDiscourse writing — the biggest marks in the paper

2. You were one of the students who cleared the canal. Write a diary entry about the last day of the work. (4)

Format (about half the marks): date, day and time at the top · first person · past tense · personal feelings and reflection, not just a list of events · no salutation, no signature.

Sample opening: 14 August 2026, Saturday, 9.30 p.m.
Today we finished. Eight weekends of pulling weed out of black water, and this evening the canal actually moved. I stood on the bank with my hands still stinging and watched it go. I keep thinking about how everyone said it was pointless — and then Anu shouted and pointed, and there was a kingfisher on the wire. I have never felt so tired or so pleased with myself.

What loses marks: writing it as a story instead of a reflection, and forgetting the date.

3. Write a notice to be put up on the school board inviting students to join the next canal-cleaning drive. (4)

Format: name of the school at the top · the word NOTICE in capitals and centred · the date of issue · a short heading · the body giving what, when, where and who can join · the writer's name and designation (e.g. Secretary, Nature Club) · the whole thing inside a box, kept brief and factual.

What loses marks: writing in the first person or adding personal feelings — a notice is impersonal and purely informative.

4. Write a letter to the Secretary of the local council thanking them for installing the waste screens and requesting two more. (6)

Format: sender's address · date · receiver's address · salutation (Dear Sir/Madam) · subject line · body in three paragraphs — who you are and why you are writing, the details, the specific request · Yours faithfully · signature and name.

Content: paragraph 1 identify yourself and the project; paragraph 2 report what has improved since the screens went in; paragraph 3 make the request, saying exactly where the two new screens are needed and why.

Note: "Yours faithfully" goes with "Dear Sir/Madam"; "Yours sincerely" goes with a named person. Mixing them costs a mark.

SECTION CLanguage elements

5. Edit the paragraph — there are four errors. The students was working every weekend. Each of them have a task. They have clear the weed by August. Now the canal is more cleaner than before.

The students were working every weekend. Each of them has a task. They had cleared the weed by August. Now the canal is cleaner than before.

The four error types they plant most often: subject–verb agreement (were), 'each' taking a singular verb (has), wrong participle form (had cleared), and double comparatives (cleaner, not more cleaner).

6. Add question tags. (a) The canal is clean now, __________ ? (b) They didn't give up, __________ ?

(a) isn't it? (b) did they?
Positive statement → negative tag, and the reverse. Repeat the auxiliary and turn the subject into a pronoun.

7. Change into reported speech: The teacher said to us, "You have done excellent work."

The teacher told us that we had done excellent work.
Three shifts: 'said to' → 'told', 'you' → 'we', and present perfect → past perfect.

8. Fill in with the right word. (a) They have been working on the canal __________ March. (since / for) (b) The drive was __________ because of the rain. (put off / put up with) (c) He worked hard, __________ he did not give up. (and / but / so)

(a) since — a point in time.
(b) put off — postponed.
(c) and — the two clauses agree with each other rather than contrast.

End of practice paperStructure to confirm with your school

Built from real papers. The structure below is taken from the real Summative Assessment Term I 2025-26 Class 9 Social Science paper and the SCERT model paper, which agree exactly: 30 questions, 80 marks, 2½ hours. Every question is compulsory — the only choice is an either/or inside the 3, 4 and 5-mark questions.

FIRST TERMINAL EVALUATION 2026–27

STANDARD IX · SOCIAL SCIENCE

Time: 2½ HoursTotal Score: 80

Instructions: First 15 minutes are reading and planning time. Answer all questions. Where a question offers a choice, answer only one alternative.

SECTION IQuestions 1–8 · 1 score each (8 × 1 = 8)

1. Who wrote the Arthashastra?

Kautilya (also known as Chanakya).

2. The Government of India signs a defence agreement with another country. Which list of the Seventh Schedule does this fall under?

Union List. Defence and foreign affairs belong exclusively to the Centre.

3. Which is the northernmost and highest range of the Himalayas?

Himadri (the Greater Himalaya).

4. Who coined the term "Neolithic Revolution"?

Gordon Childe.

5. Match column A with column B.

(i) Land	(a) Wage
(ii) Labour	(b) Interest
(iii) Capital	(c) Rent
(iv) Entrepreneurship	(d) Profit

(i)–(c), (ii)–(a), (iii)–(b), (iv)–(d)

6. Assertion (A): Rivers are not visible on the surface in the Bhabar belt.
Reason (R): The Bhabar is made of coarse porous pebbles and boulders. Are both correct? Does R explain A?

Both (A) and (R) are correct, and (R) is the correct explanation of (A). The porous material lets water sink and flow underground.

7. The Ganga originates from which glacier?

The Gangotri glacier.

8. Which of these tools belongs to the Mesolithic age? (a) polished stone axe (b) microlith (c) rough hand axe (d) copper chisel

(b) microlith — the tiny sharp blade characteristic of the Mesolithic.

SECTION IIQuestions 9–13 · 2 scores each (5 × 2 = 10)

9. What is meant by Bugyals?

High-altitude alpine meadows in the Himalayas, used as summer pasture for grazing and, when snow-covered, for winter tourism.

10. How is an alluvial fan formed?

Where a river leaves the mountains and enters the plain, the slope suddenly decreases, so the river's velocity drops and it can no longer carry its sediment. The load is deposited in a fan shape at the mountain foot.

11. Name the two sects of Jainism.

Swetambara (white-clad) and Digambara (sky-clad).

12. Complete the chart on the use of stone tools by early humans. Collecting natural stones → A → shaping stones to need → B

A – Utilisation (using stones as found). B – Standardisation (making specific tool types deliberately and repeatedly).

13. What is meant by human capital?

The economic value of a population's knowledge, skills and health — people treated as a productive asset, built up by investment in education and healthcare.

SECTION IIIQuestions 14–21 · 3 scores each (8 × 3 = 24)

14. (Either) Compare the Early and Later Vedic periods in terms of livelihood, society and worship. (Or) Which ideas of the Buddha attracted people to Buddhism?

Either: Early Vedic — semi-nomadic pastoral life with some farming, forests cleared for agriculture, simpler rituals, and a relatively higher status for women. Later Vedic — settled agriculture, larger kingdoms, elaborate and specialised sacrifices performed by priests, a more rigid varna system and a decline in women's status.

Or: His teachings were simple and practical; he rejected the caste system and Vedic sacrifice; he preached ahimsa and the Middle Path; and he taught in Pali, the language of ordinary people rather than Sanskrit.

15. Describe the climate of the Himalayan region.

The climate varies sharply with altitude — subtropical on the lower southern slopes, temperate higher up, and extremely cold with permanent snow at the greatest heights. The mountains intercept the south-west monsoon, forcing the winds to rise and giving heavy rainfall on the southern slopes, while the northern side lies in a rain shadow. Snowfall is common in winter above the tree line.

16. Write any three main features of the Lok Sabha.

It is the Lower House (House of the People) · it has 543 members, directly elected by the people · its normal term is 5 years · the minimum age to contest is 25 · it is presided over by the Speaker · money bills can originate only here.

17. Describe the Bhabar and Tarai belts of the northern plains.

Bhabar — a narrow belt of pebbles and boulders about 8–10 km wide along the foot of the Shiwaliks. It is so porous that rivers entering it disappear underground.
Tarai — immediately south, about 10–20 km wide, where those streams re-emerge, creating a marshy, swampy belt with dense forest and rich wildlife.

18. (Either) Explain how education contributes to a country's progress. (Or) Explain why poverty is an obstacle to human resource development.

Either: Education raises a worker's ability and productivity, gives the technical knowledge to use modern technology, develops skills that lead to better jobs and higher incomes, and improves overall quality of life — so it functions as an investment in human capital, not a cost.

Or: Poverty creates a trap: with no income a family cannot afford schooling or healthcare, so children remain unskilled and unhealthy, so their productivity and earnings stay low, so the family stays poor. It blocks the very investments that would end it, which is why public spending on education and health is treated as development policy.

19. Who wrote the Arthashastra, and how do the Saptanga (seven limbs) affect the survival of a state?

Written by Kautilya (Chanakya). The Saptanga are the seven limbs of the state: Swami (king), Amatya (ministers), Janapada (territory and people), Durga (fort), Kosha (treasury), Danda (army) and Mitra (allies). Kautilya argued a state is like a body — if any one limb is weak, the whole state is vulnerable, so a ruler must maintain all seven together.

20. Justify the statement: "The Athenian system resembles modern democracy."

Resemblances: decisions were taken by an assembly of citizens who debated and voted; office-holders were accountable; laws applied to all citizens alike.
But the crucial difference: citizenship was limited to free adult males over 30 — women, slaves and foreigners were excluded. Modern democracy rests on universal adult franchise. So Athens resembles it in method but not in reach.

21. Name the stone ages in order and give the characteristic tool of each.

Palaeolithic — rough, unpolished tools: hand axes, choppers, spears. Mesolithic — microliths, tiny sharp blades, and the bow and arrow. Neolithic — polished and ground stone tools and composite tools with handles.

SECTION IVQuestions 22–28 · 4 scores each (7 × 4 = 28)

22. (Either) Explain the changes brought about by the Neolithic Revolution. (Or) Describe the first urbanisation in Indian history.

Either: Humans began agriculture and the domestication of animals, so they settled permanently and villages appeared. Polished stone tools and pottery for storage were made. A food surplus became possible, which freed some people from food production and allowed occupational specialisation — and control of that surplus produced the first differences in wealth and power.

Or: The Harappan (Indus Valley) civilisation — cities such as Harappa, Mohenjodaro and Lothal, with planned streets on a grid, sophisticated covered drainage, granaries for storing surplus grain, standardised baked bricks and weights, and craft production and trade.

23. (Either) Describe the divisions of the northern plains from north to south. (Or) Explain the causes of flooding in the northern plains.

Either: Bhabar (pebbles and boulders, rivers vanish underground) → Tarai (marshy, rivers re-emerge, dense forest) → the alluvial plain proper, divided into Bhangar (older alluvium above flood level, less fertile, with kankar nodules) and Khadar (newer floodplain alluvium, renewed by silt each flood, highly fertile, with riverine islands, sandbars and braided streams). The plain stretches about 3,200 km and is the largest alluvial plain in the world.

Or: Heavy concentrated monsoon rainfall · very gentle gradient so water drains slowly · heavy siltation raising river beds above the surrounding land · deforestation in the Himalayan catchment increasing runoff · and embankment failure and unplanned construction blocking natural drainage.

24. Describe the three phases in the development of tourism in the Himalayas.

1. Pilgrimage — the oldest phase, drawing travellers for centuries to Kailas, Amarnath, Hemkund and other sacred sites.
2. Colonial hill stations — in the 19th century the British developed Shimla, Darjeeling and Nainital as summer retreats from the heat of the plains.
3. Adventure tourism — after the first ascent of Everest in 1953, trekking, mountaineering, skiing and river sports became major attractions.

25. List and explain the main features of Indian federalism.

Division of powers between the Centre and the states through the Union, State and Concurrent Lists · supremacy of a written Constitution that binds both levels · an independent judiciary to settle Centre–state disputes · a bicameral legislature, with the Rajya Sabha representing the states · and, distinctively for India, single citizenship for the whole country rather than separate state citizenship.

26. Which factors strengthen the formation of human capital?

Education — raises ability, skills and the capacity to use technology. Healthcare — a healthy worker is more productive and misses less work. On-the-job training and skill development — matches skills to real work. Migration — moving to where opportunities are better raises returns on the same skills. Access to information — lets people find jobs, markets and services.

27. Justify: "The Constitution ensures a balanced separation of legislative, executive and judicial powers."

The legislature (Parliament and state assemblies) makes law; the executive (President, Council of Ministers, administration) implements it; the judiciary (Supreme Court and High Courts) interprets it and tests it against the Constitution. Each is given its own sphere so that no single organ can dominate. The judiciary's independence — security of tenure and salaries — lets it strike down unconstitutional laws or executive actions, while the legislature controls the executive through questions, debate and the confidence of the House. This mutual checking is what makes the balance real rather than nominal.

28. Mark the following on an outline map of India: Shiwalik, Karakoram, Himadri, Naga Hills.

Karakoram — far north, beyond the main Himalaya, in the trans-Himalayan zone (Kashmir/Ladakh region).
Himadri — the continuous northernmost range of the main Himalaya, running north-west to south-east.
Shiwalik — the southernmost, lowest Himalayan range, just above the northern plains.
Naga Hills — in the far north-east, part of the eastern hills bordering Myanmar.
Practise this on a real outline map — a map question of this type appears in the SCERT model paper.

SECTION VQuestions 29–30 · 5 scores each (2 × 5 = 10)

29. (Either) Explain the geographical factors that helped Magadha grow into the most powerful of the Mahajanapadas. (Or) Compare Buddhism and Jainism.

Either: Fertile alluvial land along the Ganga gave a large, reliable agricultural surplus, which could be taxed to feed a standing army. Iron ore deposits nearby supplied both better weapons and better ploughs — and the ploughs raised the surplus further, reinforcing the advantage. Forests with elephants provided war elephants and timber. The Ganga and its tributaries offered cheap transport for trade, revenue and troop movement. Finally, rulers such as Bimbisara and Ajatashatru deliberately exploited these advantages through conquest, alliance and marriage — geography created the opportunity, but leadership used it.

Or: Both arose in the 6th century BCE in the same region, both rejected Vedic ritual sacrifice and the caste system, both preached non-violence and taught in the people's languages, and both were supported by merchants and rulers. Differences: Buddhism follows the Middle Path and its Three Jewels are right faith, knowledge and action; Jainism demands far stricter asceticism and an absolute ahimsa. Buddhism split into Mahayana and Hinayana; Jainism into Swetambara and Digambara. Buddhism spread widely outside India; Jainism remained largely Indian.

30. (Either) Describe the characteristics of the Western Himalayas. (Or) Describe the soils of the northern plains.

Either: The Western Himalaya lies between the Indus and the Kali/Sutlej rivers and covers Kashmir, Himachal and Uttarakhand. It shows all three parallel ranges — Himadri, Himachal and Shiwalik — plus the trans-Himalayan Karakoram, Ladakh and Zaskar ranges to the north. Features include the Kashmir valley with its humus-rich Karewa terraces used for saffron, flat Duns between the Lesser Himalaya and the Shiwaliks, alpine Bugyal meadows, and high passes such as Banihal, Rohtang and Baralacha La. K2, the highest peak in India, lies here. Its economy rests on terraced agriculture, horticulture, animal herding and tourism — pilgrimage centres, colonial hill stations like Shimla, and modern adventure tourism.

Or: The dominant soil is alluvial, deposited by the rivers and among the most fertile in the world. It divides into Bhangar — older, above flood level, less fertile, often containing calcareous kankar nodules — and Khadar — newer floodplain soil, replenished with fresh silt at every flood and therefore highly productive. Along the northern edge the Bhabar is coarse and porous and the Tarai is marshy and humus-rich. Towards the deltas, especially the Sundarbans, soils become saline, and in the western margins towards Rajasthan they become arid and sandy.

End of question paperTotal: 8 + 10 + 24 + 28 + 10 = 80 scores

Built from the SCERT model paper. Structure taken from the genuine SCERT Model Question Paper, First Term 2025-26 and cross-confirmed by two real Pareeksha Bhavan answer keys: 18 questions, 40 marks, 1½ hours. Answer everything — the only choice is an either/or inside a few questions. Exactly the same shape as the Chemistry paper.

FIRST TERMINAL EVALUATION 2026–27

STANDARD IX · BIOLOGY

Time: 1½ HoursTotal Score: 40

Instructions: First 15 minutes are reading and planning time. Answer all questions. Where a question offers a choice, answer only one alternative.

SECTION IQuestions 1–4 · 1 score each (4 × 1 = 4)

1. Where does digestion begin in Hydra? (a) tentacles (b) mouth (c) body cavity (d) food vacuole

(c) body cavity. Food enters through the mouth, but digestion begins extracellularly in the body cavity.

2. Assertion (A): The light phase of photosynthesis occurs only in the presence of light.
Reason (R): Water is split during the light phase. Are both correct? Does R explain A?

Both (A) and (R) are correct, and (R) is the correct explanation of (A). Photolysis — the splitting of water — requires light energy, which is why the phase cannot proceed in darkness.

3. The dark phase of photosynthesis takes place in the __________.

Stroma of the chloroplast. (The light phase takes place in the grana.)

4. Which transport process requires energy? (a) diffusion (b) osmosis (c) facilitated diffusion (d) active transport

(d) active transport — it moves substances against the concentration gradient, so ATP is spent.

SECTION IIQuestions 5–11 · 2 scores each (7 × 2 = 14)

5. The liver produces no digestive enzyme, yet it plays a major role in digestion. Why?

It produces bile. Bile contains no enzymes but emulsifies fats — breaking large globules into tiny droplets, greatly increasing the surface area for lipase to act on. The liver also processes nutrients arriving through the hepatic portal vein.

6. Glucose enters a cell without the cell spending any energy, but it needs help to cross the membrane. (a) Name the process. (b) Explain how it works.

(a) Facilitated diffusion.
(b) Glucose is too large and polar to pass through the lipid membrane on its own, so a carrier protein in the membrane binds it and moves it across. The movement is still down the concentration gradient, so no energy is required.

7. A student claims: "Digestion is the same in Hydra and Amoeba." Is the student right? Justify.

No. In Amoeba digestion is entirely intracellular — food is engulfed into a food vacuole where enzymes act inside the single cell. In Hydra food enters the body cavity where digestion begins extracellularly, and is completed intracellularly by the lining cells.

8. (Either) Two people are described — one eats mostly fried and oily food, the other mostly fruits and vegetables. Which habits are harmful, and name two circulatory diseases linked to them. (Or) Explain why marine pollution is a serious threat to ecosystems.

Either: The fried and oily diet is harmful. Excess saturated fat raises blood cholesterol, which deposits in artery walls, narrowing them. Diseases: atherosclerosis, high blood pressure (hypertension) and heart attack.

Or: Marine algae and phytoplankton are the primary producers of the ocean and generate a very large share of atmospheric oxygen. Pollution kills them and the organisms that feed on them, so it damages both the ocean food chain and the planet's oxygen supply.

9. What is homeostasis? Give one example from the human body.

The maintenance of a stable internal environment — temperature, water and salt balance, pH, blood glucose — despite changes in the surroundings. Example: sweating cools the body when the temperature rises; shivering generates heat when it falls.

10. Identify the fluid between the layers of the pericardium and describe its function.

Pericardial fluid. It cushions and protects the heart and reduces friction between the heart and surrounding tissue as it beats.

11. Name the three plasma proteins and state which is involved in clotting.

Albumin, globulin and fibrinogen. Fibrinogen is involved in blood clotting.

SECTION IIIQuestions 12–17 · 3 scores each (6 × 3 = 18)

12. (Either) Rhoeo leaf cells are placed in a concentrated salt solution and in pure water. Describe what happens in each, and explain the role of the membrane. (Or) Name the two nutrients produced in photosynthesis, explain why glucose is converted to starch, and comment on the importance of sucrose.

Either: In concentrated salt solution the cell loses water by osmosis and the protoplasm shrinks away from the cell wall — plasmolysis. In pure water water enters the cell, which becomes swollen and turgid. The plasma membrane is selectively permeable — it lets water pass but restricts solutes, which is what makes osmosis directional.

Or: The products are glucose and oxygen. Glucose is soluble and would upset the cell's osmotic balance, so it is converted into starch, which is insoluble and compact — ideal for storage. Sucrose is the form in which sugar is transported through the phloem to the rest of the plant.

13. Explain why food does not normally enter the windpipe while swallowing, but sometimes does when you talk while eating.

During swallowing, a flap of cartilage called the epiglottis automatically closes over the opening of the windpipe, so food is directed into the oesophagus. When you talk or laugh while swallowing, the windpipe must open for air, so the epiglottis may not close in time — food enters the trachea and triggers a protective cough.

14. (Either) Draw and label a tooth, marking the hard non-living outer part and the calcium-containing layer beneath it. (Or) Name the two absorptive structures in a villus and state which nutrients each absorbs.

Either: Label enamel (hardest, non-living, outermost), dentine (bone-like calcium-containing layer beneath), pulp cavity (nerves and blood vessels) and cementum (covers the root, anchors the tooth).

Or: Blood capillaries — absorb glucose and amino acids, which travel via the hepatic portal vein to the liver. Lacteal — absorbs fats, which travel through the lymphatic system.

15. Compare arteries, veins and capillaries.

Arteries — carry blood away from the heart, thick muscular elastic walls, narrow lumen, blood under high pressure, no valves (except at the heart). Usually carry oxygenated blood, except the pulmonary artery.
Veins — carry blood towards the heart, thinner walls, wider lumen, low pressure, valves prevent backflow. Usually deoxygenated, except the pulmonary vein.
Capillaries — one-cell-thick walls, connect arteries to veins, and are where exchange of gases and nutrients with tissues actually happens.

16. "Photosynthesis is both catabolic and anabolic at the same time." Evaluate this statement.

The statement is correct. In the light phase, water molecules are split (photolysis) — a breaking-down reaction, which is catabolic. In the dark phase, carbon dioxide is built up into glucose — a synthesis reaction, which is anabolic. Because both phases are part of one overall process, photosynthesis is simultaneously catabolic and anabolic.

17. A chloroplast diagram shows parts P and Q. Identify them, describe the structure of P, and explain how the two work together.

P = grana — stacks of disc-shaped membrane sacs called thylakoids, which contain the chlorophyll. Q = stroma — the fluid-filled space surrounding the grana.
The grana trap light energy and split water, producing energy carriers and oxygen. Those energy carriers pass into the stroma, where they drive the conversion of carbon dioxide into glucose. So the light phase in P supplies the energy that the dark phase in Q uses to build sugar — neither works without the other.

SECTION IVQuestion 18 · 4 scores (1 × 4 = 4)

18. (Either) In a heart diagram, chamber A is on the right side and chamber B is on the left. Compare their blood, name part C which separates them, and explain the direction of blood flow. (Or) Digestive juices A, B and C are secreted in the mouth, stomach and small intestine. Identify them, name the protein-digesting enzymes, and explain the role of hydrochloric acid.

Either: A (right side) carries deoxygenated blood received from the body through the vena cava, and pumps it to the lungs through the pulmonary artery. B (left side) carries oxygenated blood received from the lungs through the pulmonary vein, and pumps it to the whole body through the aorta. C is the septum, the muscular wall that separates the two sides and prevents oxygenated and deoxygenated blood from mixing. Flow: body → right side → lungs → left side → body.

Or: A = saliva (mouth, contains salivary amylase which digests starch). B = gastric juice (stomach, contains pepsin). C = pancreatic and intestinal juice (small intestine, contains trypsin and peptidases). The protein-digesting enzymes are pepsin and trypsin. Hydrochloric acid makes the stomach contents acidic, which activates pepsinogen into pepsin, provides the acidic pH pepsin needs to work, and kills bacteria in the food.

End of question paperTotal: 4 + 14 + 18 + 4 = 40 scores

Tap the card to flip it. Then be honest: Got it removes the card from the deck, Again pushes it back a few places so it returns until it sticks. The deck is shuffled every time you start, so you learn the fact and not its position.

0 left 0 learned

This tab is for understanding, not answering. Everything else in this app tests you. This explains why each thing is true and how it was derived, so that if the exam rephrases a question you can rebuild the answer instead of hunting for a memory. Tap any card to open it.

1 · Deriving the three equations of motion All three come from one straight-line graph. If you can draw it, you never have to memorise them.

The one picture everything comes from

Draw a velocity–time graph for a body with uniform acceleration. It starts at velocity u at time 0 and reaches v at time t. Because the acceleration is constant, the graph is a straight line — that single fact is what makes all three equations possible.

First equation — from the slope

Acceleration is defined as the rate of change of velocity, which on this graph is the slope:

a = (v − u) / t

Multiply both sides by t and rearrange:

v = u + at

Second equation — from the area

The area under a velocity–time graph is the displacement (that is proved in the next card). Our shape is a rectangle sitting under a triangle:

Rectangle: height u, width t → area = ut
Triangle: base t, height (v − u) → area = ½ × t × (v − u)

But from the first equation, (v − u) = at. Substitute that in:

s = ut + ½ × t × (at) = ut + ½at² s = ut + ½at²

Third equation — eliminating time

The whole shape is a trapezium, so its area is the average height times the width:

s = ½(u + v) × t

Now we want an equation with no t in it. From the first equation, t = (v − u)/a. Substitute:

s = ½(u + v) × (v − u)/a = (v² − u²) / 2a

Multiply both sides by 2a and rearrange:

v² = u² + 2as

How to choose which one to use

The question mentions time and asks for velocity → v = u + at
The question mentions time and asks for distance → s = ut + ½at²
The question gives you a distance and no time at all → v² = u² + 2as. This is the giveaway: braking distance, stopping distance, height reached.

Where students lose marks: dropping the ut term when u ≠ 0, and using the wrong equation because they didn't notice time was missing from the question.

2 · Why the area under a v–t graph is the displacement Not a rule to memorise — it falls out of what "distance = speed × time" means.

Start with constant velocity

If a body moves at a steady 5 m/s for 4 s, it covers 20 m. On a velocity–time graph that motion is a flat line at height 5, from t = 0 to t = 4. The rectangle under it has area 5 × 4 = 20 — the same number. That is not a coincidence: the graph's height is the speed and its width is the time, so the area is speed × time, which is the distance.

Now make the velocity change

If the velocity is changing, chop the journey into very thin time slices. Inside each slice the velocity barely changes, so each thin strip's area is that slice's distance. Add all the strips and you have the total distance — which is exactly the area under the whole curve.

height = velocity×width = time=area = displacement

The same logic gives you the slope rule

Slope means "how much the vertical changes per unit of horizontal". On a v–t graph that is change in velocity per unit time — the definition of acceleration. So slope = acceleration and area = displacement, and neither needs memorising once you see where they come from.

The mix-up to avoid: on a distance–time graph the slope is speed and the area means nothing. Check the y-axis label before you do anything.

3 · Why light bends at all Refraction is not a rule light obeys. It is the unavoidable result of light slowing down.

The one cause

Light travels at 3 × 10⁸ m/s in vacuum but slower inside matter, because the light wave keeps being absorbed and re-emitted by the atoms it passes. Refractive index is just a name for how much slower: n = c / v. Glass with n = 1.5 slows light to two-thirds of its vacuum speed.

Why slowing down causes bending

Picture a marching band walking in a straight row, crossing at an angle from a road onto mud. The row does not arrive all at once — one end reaches the mud first and slows down while the other end is still on the road going fast. The row pivots. The band is now marching in a new direction, and nobody chose to turn.

A light wavefront does exactly this. Hitting the boundary obliquely, one edge enters the denser medium and slows while the other edge is still fast, so the wavefront swings round — towards the normal when entering a denser medium, away from it when leaving.

This also tells you when light does NOT bend: if the ray hits along the normal (i = 0°), every part of the wavefront slows at the same instant, so there is nothing to pivot. The ray goes straight through — slower, but undeviated.

What changes and what doesn't

The source sets how many waves leave per second, and the boundary cannot swallow or create waves. So the same number must arrive per second on the other side: frequency is unchanged. But speed = frequency × wavelength, so if the speed drops and the frequency is fixed, the wavelength must shrink.

The classic 1-mark trap: "which does not change during refraction?" Students say wavelength. It is frequency.

4 · Where the critical angle actually comes from sin C = 1/n is not arbitrary — it's the moment Snell's law runs out of answers.

Set up the situation

Light is inside glass (denser) heading out into air (rarer). Going denser → rarer, it bends away from the normal, so the angle of refraction is always bigger than the angle of incidence.

Push the angle up and watch what happens

Snell's law across the boundary says n sin i = sin r (taking air's index as 1). As you increase i, r grows faster and reaches 90° — grazing along the surface — while i is still well short of 90°. Call that special incidence angle C. Put r = 90° into Snell's law:

n sin C = sin 90° = 1 sin C = 1 / n

And beyond C?

Push i past C and Snell's law would need sin r greater than 1 — which is impossible. There is no refracted ray to be had. So all the light is reflected back into the glass: total internal reflection. It is not that the light "decides" to reflect; there is simply no legal escape route.

Why a big n means a small C: sin C = 1/n, so the denser the medium, the smaller the critical angle. Diamond (n = 2.42) has C ≈ 24°, so light inside it is trapped over a huge range of angles and bounces repeatedly before escaping. That is the sparkle.

Both conditions matter. Denser → rarer alone is not enough, and i > C alone is meaningless in the wrong direction. State both.

5 · Free fall — why v = 0 at the top and what the minus sign means The single idea that unlocks every thrown-object question.

The insight

Throw a ball up. It slows, stops for an instant, then falls. That instant of zero velocity is the highest point — and it is the extra piece of information the question is secretly giving you. Every "maximum height" problem is really "solve with v = 0".

Getting the signs right

Choose a direction to call positive and stay with it. Taking up as positive, the ball's velocity starts at +u, but gravity pulls down, so a = −g. Then:

v² = u² + 2as → 0 = u² − 2gh → h = u² / 2g v = u + at → 0 = u − gt → t = u / g

Why the trip down mirrors the trip up

The same acceleration acts over the same height, so the ball takes the same time to come down and arrives back with the same speed it was thrown with (in the opposite direction). Hence total flight time = 2u/g.

Worked check with u = 30 m/s, g = 10 m/s²:
h = 30²/(2×10) = 900/20 = 45 m · t_up = 30/10 = 3 s · total flight = 6 s · landing speed = 30 m/s.

Two traps: "dropped" or "falls freely" means u = 0, not v = 0. And students halve the flight time instead of doubling the rise time.

1 · Why the shell rule is 2n² — and why the outer shell still stops at 8 Two rules that look contradictory until you see what each one is actually counting.

Where 2n² comes from

Electrons don't orbit anywhere they like; they occupy orbitals, and shell number n has n² orbitals available. Each orbital can hold at most 2 electrons (they must spin oppositely). Multiply:

maximum electrons in shell n = 2 × n² = 2n²

n = 1 (K): 2 × 1 = 2 · n = 2 (L): 2 × 4 = 8 · n = 3 (M): 2 × 9 = 18 · n = 4 (N): 2 × 16 = 32

So why is calcium 2,8,8,2 and not 2,8,10?

This is the bit that confuses everyone. 2n² is the shell's total capacity. But there is a second, separate rule: the outermost shell of an atom can never hold more than 8 electrons, and the shell below the outermost never more than 18.

The reason is energy. The M shell's later orbitals sit at higher energy than the N shell's first orbitals. So once M has 8 electrons, the next electron finds it cheaper to start the N shell than to keep filling M. Later, when N has begun, electrons go back and fill M up to 18 — and those elements are exactly the transition elements.

M reaches 8→N starts→M resumes filling to 18=transition series

Do not write 2,8,10 for calcium. The outermost shell caps at 8 while it is the outermost.

2 · Why the group rule adds 10 The "+10" looks like a trick. It is really a fact about the shape of the table.

The rule you were given

Valence electrons 1 or 2 → group = valence electrons
Valence electrons 3 to 8 → group = valence electrons + 10

Why the jump exists

The modern table has 18 columns. Columns 3 to 12 are the transition block — ten columns of elements whose last electron enters the penultimate shell. Those ten columns only start existing from Period 4 onward, because you need a shell below the outermost that is still unfilled.

So in Periods 2 and 3 there is a gap: after Group 2 the table jumps straight to Group 13. An element with 3 valence electrons in Period 3 (aluminium, 2,8,3) sits in the first column after that ten-column gap — Group 3 + 10 = Group 13. The +10 is literally counting the missing transition columns.

Reading it backwards

Exams often go the other way: "Period 3, Group 13 — write the configuration." Reverse each step: Period 3 → 3 shells; Group 13 → 13 − 10 = 3 valence electrons → 2,8,3.

Helium is the exception. It has 2 valence electrons but sits in Group 18, because chemically it is a noble gas — its shell is full. Don't apply the rule to it.

3 · Why atomic size shrinks across a period and grows down a group One tug-of-war explains both trends, and the reasons carry as many marks as the trends.

The tug-of-war

An atom's size is set by a contest between two things: the nucleus pulling electrons in (stronger with more protons) and the number of shells pushing the outer electrons out.

Across a period — size decreases

Move from sodium (2,8,1) to chlorine (2,8,7). The number of shells does not change — still three. But protons go from 11 to 17, so the nuclear charge rises with nothing new to shield it. The stronger pull drags the same shells inward, so the atom gets smaller.

Down a group — size increases

Move from lithium (2,1) to sodium (2,8,1) to potassium (2,8,8,1). Each step adds a whole new shell. The outermost electron is now much further out, and the inner shells shield it from the nucleus. Distance and shielding both win, so the atom gets bigger — even though the nucleus also gained protons.

across → charge up, shells same=smaller down → new shell + shielding=bigger

Answering the exam version

They give three atomic numbers in the same period and ask you to order them by size. Same period means the trend applies: higher atomic number = smaller atom. Then justify with the reason above — the justification is usually worth more than the ordering.

4 · Why atoms bother forming ions at all Everything about ion formation is one drive: get to a noble gas configuration.

What makes noble gases special

A full outer shell is a low-energy, stable arrangement, and there is a big energy gap before the next shell begins. Noble gases already have this, which is why they barely react. Every other atom is, in effect, trying to reach the same arrangement.

Lose or gain — whichever is cheaper

Metals have 1–3 valence electrons. Shedding those few empties the shell and exposes the full one beneath. Cheap. → they lose electrons, becoming positive.

Non-metals have 5–7 valence electrons. Gaining the missing 1–3 completes the octet. Cheaper than losing five. → they gain electrons, becoming negative.

That is why the charge is predictable: sodium (2,8,1) loses one → Na⁺; magnesium (2,8,2) loses two → Mg²⁺; oxygen (2,6) gains two → O²⁻; chlorine (2,8,7) gains one → Cl⁻.

Writing the equation, which is what earns the mark

Na → Na⁺ + e⁻ Mg → Mg²⁺ + 2e⁻ Al → Al³⁺ + 3e⁻ O + 2e⁻ → O²⁻ Cl + e⁻ → Cl⁻

The follow-up they always ask

"Which noble gas has the same configuration as this ion?" Count the ion's electrons and match. Na⁺ has 10 → neon. O²⁻ has 10 → neon. Cl⁻ has 18 → argon. Ca²⁺ has 18 → argon.

Protons never change. Ca²⁺ still has 20 protons — it lost electrons, not protons. That exact question appeared in the real 2025-26 paper.

5 · Why the periodic table was rebuilt around atomic number Mendeleev was nearly right. The story of how he was fixed is itself an exam question.

What Mendeleev did

He arranged the known elements in order of atomic mass and found that chemical properties repeated periodically. It worked well enough that he left gaps for undiscovered elements and predicted their properties — and was proved right.

The problem he could not fix

To keep elements with similar chemistry in the same column, he sometimes had to break his own ordering. Tellurium (mass 127.6) had to be placed before iodine (mass 126.9) so that iodine could sit with the other halogens. By mass that is backwards. He knew it was wrong but could not say why.

Moseley's fix

Henry Moseley measured the X-rays each element emits and found they depended on a whole number that turned out to be the number of protons — the atomic number. Reorder by atomic number and the anomalies vanish: tellurium is 52, iodine is 53, so tellurium comes first legitimately.

Modern periodic law: properties are a periodic function of ATOMIC NUMBER

This also explains why properties repeat at all. Atomic number fixes the electron count, which fixes the configuration, which fixes the number of valence electrons — and valence electrons are what chemistry actually depends on.

atomic number→electron count→configuration→valence electrons→properties

1 · Why format is half the marks in discourse questions Each discourse exists to do a different job. The format is the job made visible.

The principle

A discourse is not a style of writing, it is a purpose. Once you know the purpose, the format stops being a list to memorise and becomes obvious.

Diary — purpose: to process your own day privately. So: a date (which day), first person, past tense, and feelings. No salutation, no signature — you are not addressing anyone.

Notice — purpose: to inform many strangers of a fact. So: institution name, the word NOTICE, date, and the what/when/where/who. No feelings, no "I" — it is impersonal by design.

Letter — purpose: to reach one named person and get a response. So: both addresses (it must travel), date, salutation, subject, body, closing, signature.

Conversation — purpose: to show two minds interacting. So: named turns with a colon, short natural sentences, and each turn responding to the last.

Character sketch — purpose: to convince a reader of your reading of a person. So: traits, each one backed by evidence from the text.

Speech — purpose: to move a live audience. So: greeting, hook, ordered argument, call to action, thanks.

How to use this in the exam

Before writing a word, ask "what is this piece of writing supposed to achieve?" The format follows. Then write the format skeleton on your answer sheet first and fill it — that way you bank the format marks even if you run short of time on content.

The most common failure: writing a diary entry as a story of what happened. The events are only the setting — the marks are in the reflection on them.

2 · Why tenses shift in reported speech Backshift isn't a rule to memorise. It's what happens when "now" becomes "then".

The idea

When someone speaks, they anchor everything to their moment. When you report it later, your moment has moved on. So every word that pointed to the speaker's "now" has to be re-pointed to your "then". That is all backshift is.

Time words shift: now → then · today → that day · tomorrow → the next day · yesterday → the previous day · here → there · this → that

Tenses step back: present simple → past simple · present continuous → past continuous · present perfect → past perfect · will → would · can → could · may → might

Worked example

Ravi said to me, "I am going to the library."

Reporting verb: "said to" takes an object, so it becomes told → Ravi told me…
Pronoun: Ravi's "I" is Ravi, and from my viewpoint that is he.
Tense: "am going" was present for him, so it steps back to was going.

Ravi told me that he was going to the library.

The exception that proves the logic

"The teacher said, 'The earth revolves around the sun.'" → "The teacher said that the earth revolves around the sun." No backshift — because it is still true now. Backshift exists to preserve accuracy about time, so where time doesn't matter, it doesn't apply.

Questions and commands change shape

Question → use asked, drop the question word order, keep the question word: "Where do you live?" → He asked her where she lived.
Command → use told / ordered + infinitive: "Don't waste time." → Mother told me not to waste my time.

3 · Question tags as a three-step algorithm There is nothing to understand here — but there is a procedure that never fails.

The procedure

Find the auxiliary verb in the statement (is, are, was, were, have, has, had, will, can, should…). If there isn't one, the verb is a plain present or past tense, so the auxiliary is do / does / did.
Flip the polarity. Positive statement → negative tag. Negative statement → positive tag.
Turn the subject into a pronoun. "The children" → they. "Ravi" → he.

She is a doctor → auxiliary is, statement positive → isn't she?
Ravi went to school → no auxiliary, past tense → did; positive → didn't he?
They didn't come → auxiliary did, statement negative → did they?
You will help me → auxiliary will, positive → won't you?

Hidden negatives count. Words like never, hardly, seldom, nobody, nothing make a sentence negative even without "not", so the tag goes positive: "He never comes late, does he?"

4 · How to read a comprehension question for its mark value The number in brackets is an instruction about length. Most students ignore it.

The marks tell you the shape of the answer

1 mark → one fact, one sentence. Lifting the phrase from the passage is fine.
2 marks → two distinct points, or one point plus its reason.
3–4 marks → three or four points, in your own words, each traceable to the passage.

Read the question's verb

"What…" wants a fact — find it and state it. "Why…" wants a cause — your answer must contain because or its equivalent. "How…" wants a process or method — give the steps. "Why does the writer mention…" is different from all of these: it asks about the writer's purpose, so the answer is about the effect on the reader, not about the fact itself.

The method

Read the whole passage once for the gist. Don't stop at unknown words.
Read the questions — now you know what to hunt for.
Read again, marking the lines that answer each question.
Write in complete sentences, reusing the question's own words to start your answer.

Never leave a comprehension question blank. The answer is on the page in front of you — this is the one section where nothing has to be remembered.

1 · The four transport processes, sorted by two questions Stop memorising four definitions. Ask two yes/no questions instead.

The two questions

Every membrane-transport question in this chapter can be answered by asking: (1) Does it need energy? and (2) Does it need a carrier protein?

No energy, no carrier → Diffusion (or osmosis if the thing moving is water across a selectively permeable membrane).

No energy, but needs a carrier → Facilitated diffusion. The molecule is too big or too polar to slip through the lipid membrane alone, so a protein ferries it — but still downhill, from high to low concentration.

Needs energy → Active transport. This is the only one that goes against the concentration gradient, and going uphill is precisely why it costs ATP.

Why osmosis has its own name

Osmosis is just diffusion, but of water, through a membrane that lets water pass and holds solutes back. Water moves from where it is more abundant (dilute solution) to where it is scarcer (concentrated solution). That direction is the whole of it — every raisin, potato and Rhoeo-leaf question is asking which side is more concentrated.

Raisin in pure water → outside is dilute, inside is concentrated → water goes in → it swells.
Plant cell in strong salt solution → outside is concentrated → water goes out → the protoplasm shrinks from the wall → plasmolysis.

The trap: students say active transport whenever a carrier protein is mentioned. Carrier protein alone means facilitated diffusion. Only "against the gradient" or "uses ATP" means active transport.

2 · Photosynthesis: two phases, two places, two jobs Grana and stroma aren't trivia — the division of labour between them is the answer to several questions.

The split

Light phase — in the GRANA (stacks of thylakoid discs holding the chlorophyll). Light energy is captured and used to split water — photolysis. This releases oxygen as a by-product and produces energy carriers.

Dark phase — in the STROMA (the fluid around the grana). The energy carriers from the light phase are used to build glucose from carbon dioxide. It doesn't need light directly, but it does need what the light phase produced — which is why it stops in prolonged darkness.

Why this answers the "catabolic and anabolic" question

Splitting water is breaking down — catabolic. Building glucose from CO₂ is building up — anabolic. Both happen inside the same overall process, so photosynthesis is genuinely both at once. Notice the answer is just the two-phase split restated.

And why the two parts depend on each other

grana capture light→energy carriers→stroma builds sugar

The grana supply the energy; the stroma spends it. Neither works alone — which is exactly what the 3-mark chloroplast-structure question is asking you to explain.

What happens to the glucose

Glucose is soluble, so leaving it loose would disturb the cell's osmotic balance. It is converted into starch, which is insoluble and compact, for storage — and into sucrose for transport through the phloem.

3 · Why digestion looks different in Amoeba, Hydra and us One principle — surface area versus body size — explains all three.

The principle

Every cell must get nutrients across its own membrane. How an animal digests depends on how far food is from the cells that need it.

Amoeba — one cell. Food can simply be engulfed by pseudopodia into a food vacuole, and enzymes act inside the cell. Purely intracellular. Nothing more is needed because every part of the organism is already at the surface.

Hydra — many cells, but only two layers thick. Food enters the mouth into a body cavity, where enzymes are secreted and digestion begins extracellularly; the lining cells then take up the fragments and finish digesting them intracellularly. A hybrid, because a cavity is now needed but every cell still borders it.

Humans — thick, complex bodies. Digestion is entirely extracellular, in a long specialised tube, and the products must then be absorbed and transported by blood and lymph to cells that may be a metre away.

Which is why we need villi

A long tube gives a big problem: enough absorptive surface. Hence villi — millions of finger-like projections that multiply the surface area of the small intestine. Each contains blood capillaries (taking glucose and amino acids to the hepatic portal vein and the liver) and a lacteal (taking fats into the lymphatic system, which bypasses the liver at first).

The exam version: "Is digestion the same in Hydra and Amoeba?" The answer is no, and the marks are in the words intracellular and extracellular, not in the yes/no.

4 · The heart's design problem, and how the septum solves it Why the heart has four chambers and two separate circuits.

The problem

Blood must do two different journeys: to the lungs to collect oxygen, and to the body to deliver it. If oxygenated and deoxygenated blood mixed, every tissue would receive a diluted supply and the whole system would be less efficient.

The solution

Right side — receives deoxygenated blood from the body through the vena cava, pumps it to the lungs through the pulmonary artery. This is pulmonary circulation.

Left side — receives oxygenated blood from the lungs through the pulmonary vein, pumps it to the whole body through the aorta. This is systemic circulation.

The septum — the muscular wall between them, which keeps the two apart.

body→right side→lungs→left side→body

Two details examiners like

The pulmonary artery is the one artery carrying deoxygenated blood, and the pulmonary vein is the one vein carrying oxygenated blood — because artery and vein are defined by direction relative to the heart, not by oxygen content. And the left ventricle has a thicker wall than the right, because it must push blood around the entire body rather than just to the lungs next door.

The cardiac cycle in order

Atrial systole (atria contract, filling the ventricles) → ventricular systole (ventricles contract, blood leaves the heart) → joint diastole (everything relaxes and refills).

5 · What to actually revise, and what to leave The evidence says two chapters carry this paper. Spend your time accordingly.

What the real papers examined

Across the SCERT model paper and two real Pareeksha Bhavan answer keys (2024-25 and 2025-26), every single question fell into Chapter 1 or Chapter 2.

Chapter 1 — To Life Processes: diffusion, osmosis, facilitated diffusion, active transport, plasmolysis, photosynthesis light and dark phases, chloroplast structure, metabolism, homeostasis, autotrophic versus heterotrophic nutrition.

Chapter 2 — Digestion and Transport of Nutrients: Amoeba versus Hydra, tooth structure, villi and absorption, the epiglottis, bile and the liver, blood composition, the nutrient pathway, heart structure, cardiac cycle, pulmonary versus systemic circulation, diet and circulatory health.

Chapter 3 — the honest position

Respiration and Excretion is nominally in the Part 1 portion, but it did not appear in any of the three documents checked. No lungs, no alveoli, no nephron. That is real evidence, but it is only three documents, and Kerala first-terminals are set at school level — so it could still come.

What to do with that: learn the headline facts — nephron is the functional unit of the kidney, filtration happens at the glomerulus in Bowman's capsule, the main waste is urea, gas exchange happens at the alveoli, and plants use stomata and lenticels. That is enough to attempt a question if one appears, without eating into the time Chapters 1 and 2 deserve.

Chapters 4–6 are not in the portion at all

Behind Movements, Reproductive Health and Classification are Part 2, taught later. Zero appearances anywhere. Do not revise them for this paper.

1 · One collision explains three chapters The Himalayas, the northern plains and where Indians live are a single causal chain.

The chain

The Indian plate drifted north and collided with the Eurasian plate. Sediment trapped between them buckled upward into fold mountains — the Himalayas — and the collision is still going, which is why the range is still rising and the region is earthquake-prone.

plates collide→Himalayas rise→monsoon blocked→heavy rain + glaciers→perennial rivers→sediment carried south→northern plains built→fertile alluvium→dense population

Each link, and the exam question it answers

Mountains block the monsoon → moist winds are forced up, cool, and dump rain on the southern slopes. (Answers: climate of the Himalayan region.)

Height creates glaciers → rivers are fed by melt as well as rain, so they never dry up. (Answers: why Himalayan rivers are perennial.)

Fast mountain rivers carry sediment → on reaching the plain the slope drops, velocity falls, and the load is dumped. (Answers: how alluvial fans form; how the plains were built.)

Coarse material drops first, fine material last → hence the belts in order: Bhabar (pebbles, porous, rivers vanish underground) → Tarai (marshy, rivers re-emerge) → alluvial plain (fine silt), split into older Bhangar and newer Khadar. (Answers the whole northern plains chapter.)

Fresh silt every flood → Khadar is more fertile than Bhangar → agriculture thrives → the plains are among the most densely populated places on earth. (Answers: why population concentrates there.)

Why this is worth learning as a chain

Half a dozen separate exam questions across two chapters are the same story told from different points. Learn the chain once and you can reconstruct any of them, even a question you have not seen before.

2 · Why a food surplus created kings, priests and inequality The Neolithic Revolution's real consequence wasn't farming. It was social structure.

Before agriculture

Palaeolithic groups were small bands of hunter-gatherers, under about a hundred people, moving with the food. You cannot store meat or accumulate much when you walk everywhere, so there was little to be unequal about — and little reason for permanent leaders.

The hinge: storable surplus

Agriculture and the domestication of animals meant food could be produced deliberately and, more importantly, stored. Once a village grows more than it eats, three things follow almost automatically:

Settlement. You must stay near the fields and the granary, so permanent villages appear — along with pottery to store grain and polished tools to work the land.
Specialisation. If some people's surplus feeds others, those others are free to become potters, weavers, metalworkers, priests, soldiers. Skills deepen.
Hierarchy. Someone must control the granary, allocate land and settle disputes. Control over the surplus is power — so differences in wealth and status appear, and eventually kings, taxes, armies and states.

surplus→storage→specialisation→control→hierarchy and the state

The link forward

This is exactly the ladder that later produces the Mahajanapadas and empires. When the exam asks about the Neolithic Revolution's "transformative impact", it is this chain — not a list of tools — that earns the top band.

3 · Why geography made Magadha an empire The model answer for this is a causal argument, not a list of four advantages.

The four advantages — and what each one bought

Fertile alluvial land on the Ganga → large, reliable agricultural surplus → the state can tax heavily and feed a standing army without everyone farming.

Iron ore deposits nearby → better weapons and better ploughs. The ploughs raise the surplus further, which pays for more weapons. The two reinforce each other.

Forests with elephants → war elephants, the heavy armour of ancient India, plus timber for building and fuel.

The Ganga and its tributaries → cheap transport for trade goods, taxes and troops. Rivers move armies faster than roads did.

Add the human factor

Geography offered these; rulers such as Bimbisara and Ajatashatru chose to exploit them through conquest, alliance and marriage. Advantages do not use themselves — a full answer says so.

How to write it for 5 marks

Do not list four nouns. For each advantage, write advantage → what it enabled → why that mattered militarily or economically. Four short causal sentences plus a closing line about the rulers is a complete top-band answer.

Don't confuse the layers. Magadha was one of the 16 Mahajanapadas; the Mauryan Empire grew out of it later, founded by Chandragupta Maurya with Kautilya as adviser, with its capital at Pataliputra (Ujjayini was only a provincial capital — a favourite distractor).

4 · Why the Constitution splits power the way it does The three lists are not arbitrary. Each one answers a specific question.

The problem the framers faced

India is huge and extremely diverse — many languages, religions and regional needs. That creates two opposite requirements at once: some things must be identical everywhere or the country cannot function, while others must be decided locally or the decisions will not fit the people affected. Federalism is the answer to holding both at once.

How each list follows from that

Union List — things that only make sense nationally, or where a state acting alone would be dangerous: defence, foreign affairs, currency, railways, banking. Imagine each state with its own army or currency.

State List — things where local knowledge matters most and needs genuinely differ: police, agriculture, public health, jails.

Concurrent List — things both levels legitimately care about: education, forests, marriage. Both may legislate; if the two laws clash, the central law prevails — otherwise the system would deadlock.

The safeguards around it

Dividing power only works if the division is enforceable, which is why the Constitution adds: a written Constitution supreme over both levels, an independent judiciary to referee disputes, a bicameral legislature so states are represented at the Centre, and — distinctively for India — single citizenship, so that dividing power does not divide the nation.

Separation of powers is a different split

Don't confuse the two. Federalism divides power vertically (Centre vs states). Separation of powers divides it horizontally (legislature makes law, executive implements, judiciary interprets) so no organ can dominate. Exams ask about both, often in the same paper.

5 · Why people count as "capital" The phrase sounds cold. The economics behind it is the most tested idea in the Geography book.

Start with the four factors

Production needs four things, and each is paid differently:

Land → Rent · Labour → Wage · Capital → Interest · Entrepreneurship → Profit

"Capital" normally means produced goods used to produce more goods — machines, tools, buildings. You spend on them now because they raise output later.

The insight

Education and health do the same thing to a person that a machine upgrade does to a factory. An educated, healthy worker produces more, uses better technology, adapts to new work and earns more over a lifetime. So spending on schooling and healthcare is not consumption — it is investment, and the stock of skill and health it builds up is called human capital.

education + health→higher productivity→higher income→national development

What builds it and what blocks it

Builds it: education, healthcare, on-the-job training and skill development, migration to better opportunities, access to information.

Blocks it: poverty, which traps people — no income means no schooling or medical care, which means low productivity, which means no income. Breaking that loop is why public spending on education and health is treated as development policy, not charity.

Unemployment, classified by cause

Open — able and willing, no job at all (includes educated unemployment).
Seasonal — work exists only part of the year, typical in agriculture.
Disguised — more people working than the job needs; remove some and output is unchanged.
Structural — the job disappeared because technology or the economy's structure changed.

The SCERT model paper gives two scenarios — an educated jobseeker, and a worker replaced by a machine — and asks you to name the type. Classify by what caused it, and both are easy.

Unlimited practice. Every question here is generated fresh — same high-probability question types as the main quiz, but with different numbers, different media, different graphs each time. The graph questions draw a new graph every single time, so you can't memorise the answer. Keep hitting "8 more" until the method feels automatic.

How this guide was put together

Rather than trusting "important question" videos, this guide works backwards from the papers themselves. Three kinds of document were used:

Real Pareeksha Bhavan first-term papers and answer keys from 2024-25 and 2025-26, archived on Education Observer's forum. These are the strongest evidence available — they show what was actually asked, not what someone predicts will be asked. Chemistry, Social Science and Biology all have real papers behind them here.
SCERT model question papers, which real school papers visibly copy in structure.
The SCERT textbooks themselves, via the official Samagra portal, to confirm chapter lists and catch the 2024-25 syllabus revision.

Every question in the quizzes and mock papers is modelled on a question type that appears in one of those documents, and each answer says which. Where the evidence was thin — English especially — that is stated plainly rather than papered over with guesses.

One structural fact worth knowing before anything else: Class 9 is not a board exam. See the next card.

The thing nobody in those videos tells you

Your Class 9 exam is not a board exam. Kerala's Pareeksha Bhavan (KBPE) conducts exactly two real common state exams — SSLC (Class 10) and Plus Two. There is no state board paper for Class 9. What SCERT publishes for Class 9 is labelled, in its own words, a "Model Question Paper" — a sample. The actual first-terminal papers are set below state level (district / sub-district / school), which is why archives like Education Observer carry several different PDFs as "the" Class 9 physics first-term paper for the same year.

Three consequences, and they change how you should spend tonight:

"100% sure questions" is structurally impossible for this exam — not because the channels are dishonest, but because there is no single paper for anyone to know. For SSLC that phrase at least refers to a real common paper. For Class 9 it cannot.
Nobody fact-checks these predictions. A search for post-exam commentary — forums, news, comments — where anyone says "channel X predicted it and it came" turns up nothing, in either direction. No channel publishes an audited hit rate. That's a genuine blind spot, not evidence they're good or bad.
So chase the source material, not the prophecy. Whoever set your paper drew from the SCERT question pool and past first-term papers. Those are public. Working through them beats watching someone guess.

Do these tonight, in this order

#	Source	Why it's ranked here
1	SCERT Question Pool questionpool.scert.kerala.gov.in · Samagra portal	Official chapter-wise question bank with answer hints, published by SCERT as prep material. This is the raw stock paper-setters actually draw from. The closest thing to a legitimate "leak" that exists, and it's free and public. Start here.
2	A+ Blog — 5 first-term model papers aplusblog.in · Class 9 Physics new-pattern sets	Five complete new-pattern first-term Physics papers, English and Malayalam medium, with answer keys — page verified. Also has the Samagra first-terminal sample paper with keys. The single highest-value non-official find.
3	Education Observer forum — real past papers Class 9 first-term Physics thread	The actual 2023, 2024 and 2025 Class 9 Physics first-term papers, both mediums, several with answer keys. Real papers beat model papers. Free, may need registration to download.
4	Textbooks All — Ch 2 question bank Equations of Motion, 40 Q&A	Verified: 40 questions on Chapter 2 with full worked solutions — MCQs, definitions, numericals, graph interpretation, scenario problems. Also has Chapter 1 Q&A.
5	HSSLive Ch 1 · Ch 2 · 5 model papers	Full textbook solutions both mediums, plus five model papers. These were the basis for much of this quiz — Set 1 and Set 3 confirm the paper covers Ch 1–4 and excludes Ch 5–8 entirely.
6	A+ Blog / apluseducare — chapter notes Ch 1 Refraction Q&A (EM + MM)	Chapter-wise textbook Q&A, PDF notes, online tests, and the SCERT Teacher Text. Run by a practising teacher (Malappuram). Both mediums side by side.

If you only have two hours: item 3 (one real past paper, under timer) then item 1 (question pool for the two chapters). That combination is worth more than every prediction video put together.

YouTube — the full sweep, including the small ones

Small channels can matter, and one did turn up. But the honest ranking puts the big two on top, because they are the only ones verifiably active in 2026 and teaching the current textbook.

Channel	Verdict	Detail
Exam Winner Class 9 554K subs · ~9 uploads/week	Best overall	Verified active in 2026 and the largest by far. Chapter one-shots for Refraction, Equations of Motion and Laws of Motion (teacher: Dilsha), plus Onam-specific "important questions" videos for Physics specifically — the only channel with a confirmed one for Class 9 Physics. Watch out: an older duplicate channel "Exam Winner Class 9 2023" also exists — make sure you're on the current one.
Xylem Class 9 (State) @xylemclass9-2024	Good — check the handle	Confirmed Kerala-state Refraction of Light videos and 2026 activity. Critical: Xylem also runs @xylemcbse9. Land on the CBSE one and everything you watch is the wrong textbook — CBSE Class 9 has no Refraction of Light chapter at all.
Peecees Channel for Education small individual teacher	The small-channel find	Exactly the kind of channel you suspected. Runs a dedicated "KERALA 9 PHYSICS" playlist (20 videos) titled to the new textbook's exact chapter order — "NEW TEXT \| CLASS 9 PHYSICS \| CHAPTER 1 \| REFRACTION OF LIGHT". Narrow and on-target. Its subscriber count, last upload date and teaching quality are unverified, so treat it as a promising lead rather than a safe bet.
Eduport Class 9	Useful after, not before	Has the Class 9 Onam 2026 timetable video and posts answer-key discussion videos within hours of each paper — genuinely valuable, but that's after you've written. Notably: they have "100% sure questions" videos for Class 9 English, Hindi and Maths, but none was found for Class 9 Physics. Check the channel directly rather than trusting search.
Bio-Vision (Subhash Soman)	Blog > channel	The blog side is clearly active in 2026 and runs a "Final Touch" first-term series across Class 9 subjects, with Ch 1 and Ch 2 posts in both mediums. The video channel is thinner. Go to the blog.
KITE VICTERS / First Bell Kerala govt official	Careful — likely outdated	The one officially government-run channel, so tempting. But the Class 9 Physics episodes available look like 2020-era pandemic broadcasts, which predate the current textbook. Check the upload date and the chapter name before trusting anything here.
PW Kerala Class 9 youtube.com/@PWKeralaClass9	Easy to miss — it exists	A dedicated PW Kerala Class 9 channel does exist — @PWKeralaClass9. It is easy to miss, because searching for PW Kerala mostly surfaces @PWKeralaSSLC and @PWKeralaPlusTwoKEAM, which cover Class 10 and Plus Two only. Don't assume from those that PW skips Class 9 — it doesn't. Its size, upload frequency and subject coverage are unverified here, because YouTube blocks automated checking. Check two things in-app: that the videos are dated 2026 and not recycled from an earlier year, and that the physics chapter names match the current book — "Refraction of Light" and "Equations of Motion". If both hold, PW is a serious operation and worth the time.
PW Foundation / PW NEEV Class 9	Wrong syllabus	Different from the above — this is PW's CBSE stream. CBSE Class 9 has no Refraction of Light chapter and a different chemistry sequence. Make sure you are on the Kerala channel.
Searched for and could not confirm exist for Kerala Class 9 Physics: Vahan Learning, Winners Education, Focus Academy, Sasthram, Edumate, Brainy Bees, Padasala, and "Major Exam Online". Either they don't cover this, or they're too small to surface in search. If a friend actually uses one, that hyperlocal tip beats anything a search engine can find.

Instagram, Telegram and the rest

Instagram blocks automated checking, so the follower counts below are unverified — judge them in-app. Telegram turned out to be the more useful platform for this syllabus.

Where	What	Worth it?
Telegram — Textbooks All t.me/textbooksall	~19.1K members. Posts SCERT Kerala summative-assessment papers and answer keys for Standards 6–10, including Class 9 first-term material. Active in 2026.	Yes
Telegram — A+ Blog t.me/aplusblog	~2.37K members. Class 8 / 9 / SSLC focused — physics notes, model papers, answer keys, "Final Touch" first-term guides. Active through Aug 2026. Companion to the site ranked #2 above.	Yes
Instagram @xylem_class9 · @examwinner_class_9	Class-9-specific accounts from the two channels ranked highest above. Mirrors their video content in short form. Handles may vary — Exam Winner's own site lists a different handle in its footer, so search in-app rather than trusting a link.	Follow, don't rely
WhatsApp	No credible public Class 9 group found. Kerala Notes — a well-known Kerala student site — runs groups for SSLC and Plus One/Two only, and explicitly has none for Class 9.	Nothing here
Reddit / Quora	No Kerala-SCERT-specific discussion found at all. Results were generic CBSE/ICSE threads.	Skip

Two warnings before you go searching yourself

1 · Anyone offering a "leaked" Class 9 paper is running a scam. Paper-leak scams on Telegram and WhatsApp are a documented pattern in India, including arrests in Kerala and Karnataka. For a first-terminal exam set at school or district level, there is no single paper to leak — so the product being sold cannot exist. Don't pay, don't join, don't forward. Beyond the money, using a leaked paper is cheating, and the downside if it's real is far worse than the downside of an ordinary mark.

2 · Avoid the WhatsApp "group link" farm sites. Searching for Kerala study groups surfaces sites like zoneofwagroup / activewagroup / joinwagroupnow. These are SEO link-farms, not vetted by any school or publisher, and joining unknown groups from them carries a real spam and phishing risk.

And the boring truth: the free, legitimate sources in this tab — SCERT's question pool, three years of real past papers, five model papers with keys — are more than you can get through in two days. There is no shortcut that beats simply doing them.

These are the diagrams that earn marks. In Kerala papers a labelled diagram is worth marks on its own — if a question says "explain", draw the diagram even when it doesn't ask for one. Copy each of these onto paper by hand at least once; you will not remember them by looking.

1 · Refraction: air → glass

Chapter 1 · the diagram behind every "bends towards the normal" question

What to say: going from a rarer to a denser medium, light slows down and bends towards the normal, so r < i. Going the other way (glass → air) it bends away from the normal. A ray hitting the surface along the normal (i = 0) is not bent at all.

2 · Rectangular glass slab and lateral shift

Chapter 1 · a very common 3-mark "draw and explain"

What to say: the ray bends towards the normal entering the glass and away from the normal leaving it. Because the two faces are parallel, the two bendings are equal and opposite, so angle e = angle i and the emergent ray is parallel to the incident ray — just displaced sideways. That sideways displacement is the lateral shift, and it increases with a thicker slab or a larger angle of incidence.

3 · Critical angle and total internal reflection

Chapter 1 · the single most likely 4-mark diagram

What to say: as the angle of incidence inside the denser medium increases, the refracted ray bends further from the normal. At one particular angle — the critical angle C — the refracted ray grazes along the surface (r = 90°). Beyond that, no light escapes: it is totally internally reflected back into the denser medium. Relation: sin C = 1/n. For glass C ≈ 42°, water ≈ 49°, diamond ≈ 24°.

4 · Formation of a mirage

Chapter 1 · high-probability 3-mark explanation

What to say, in order: (1) air near the hot road becomes optically rarer; (2) light from the sky passing from denser to rarer layers bends away from the normal and curves; (3) at some layer the angle of incidence exceeds the critical angle, so total internal reflection occurs; (4) the reflected light reaches the eye from below, giving an inverted image of the sky that looks like water.

5 · Why the Sun is seen before it actually rises

Chapter 1 · atmospheric refraction, 2-mark

What to say: air density increases towards the ground, so sunlight entering the atmosphere is refracted continuously towards the normal and travels along a curved path. The observer sees the Sun in the direction the light finally arrives from — which is higher than its true position. So the Sun is visible about 2 minutes before actual sunrise and 2 minutes after actual sunset.

6 · Apparent depth — why a pool looks shallower

Chapter 1 · 2-mark reasoning or numerical

What to say: rays from the coin bend away from the normal as they leave the water. The eye traces them back in straight lines, and those backward extensions meet at a point above the real coin. So the coin — and the pool bottom — appears raised. n = real depth / apparent depth.

7 · Optical fibre

Chapter 1 · the standard application of TIR

What to say: light entering one end always strikes the core–cladding boundary at an angle greater than the critical angle, so it is totally internally reflected again and again and travels the whole length with almost no loss — even around bends. Uses: internet and telephone data transmission, and endoscopy in medicine.

8 · Distance vs displacement

Chapter 2 · the trap question in every paper

What to say: distance is the whole path length (scalar); displacement is the shortest straight line from start to finish, with direction (vector). A complete round trip gives displacement = 0 but distance equal to the full path. Displacement is never greater than distance.

9 · Motion graphs you must be able to read

Chapter 2 · guaranteed marks in Section III or IV

The four facts: slope of a distance–time graph = speed; a straight inclined line means uniform motion and a curve means non-uniform. Slope of a velocity–time graph = acceleration; area under a velocity–time graph = displacement. Nearly every graph question is one of these four.

10 · Stone thrown vertically upward

Chapter 2 · the textbook worked example, reused constantly

The three things being tested: at the highest point v = 0 (that is the whole trick); taking up as positive, a = −g on the way up; and the time up equals the time down, so total flight time is double. With u = 30 m/s and g = 10 m/s²: h = u²/2g = 45 m, t_up = u/g = 3 s, total flight = 6 s.

1 · Structure of the atom — shells and electrons

Chapter 1 · the picture behind every configuration question

What to say: the nucleus holds the protons and neutrons and therefore almost all the mass. Electrons occupy shells K, L, M, N outward. Each shell holds a maximum of 2n² electrons (K = 2, L = 8, M = 18, N = 32), but the outermost shell never holds more than 8. The number of shells gives the period; the electrons in the outermost shell give the group and the family.

2 · Thomson's model vs Rutherford's model

Chapter 1 · Section I of the real 2025-26 paper had three questions on this

What to say: Thomson pictured the positive charge spread evenly through the atom with electrons embedded in it. Rutherford's gold foil experiment showed most alpha particles passed straight through, so the atom is mostly empty space, with all the positive charge and nearly all the mass in a tiny central nucleus, and electrons revolving around it. Bohr then added that electrons occupy fixed stationary energy levels. The neutron was discovered later, by Chadwick.

3 · How an ion is formed

Chapter 1 / 3 · a guaranteed 2-mark, and they want the equation

The equation is what earns the mark: Na → Na⁺ + e⁻. Metals lose their valence electrons, and the charge equals how many they lose (Mg → Mg²⁺ + 2e⁻, Al → Al³⁺ + 3e⁻). Non-metals gain (8 − valence) electrons: O + 2e⁻ → O²⁻, Cl + e⁻ → Cl⁻. Every ion is chasing the configuration of its nearest noble gas — say which noble gas, because that is often part (b).

4 · Periodic table trends

Chapter 2 · atomic size was a full 3-mark question in the real paper

The two trends and their reasons: across a period size decreases — shells stay the same but nuclear charge grows, pulling electrons in. Down a group size increases — a new shell is added each time. Both the trend and the reason carry marks. Also know: Group 1 alkali metals, Group 2 alkaline earth metals, Groups 3–12 transition elements (last electron enters the penultimate shell), Group 17 halogens, Group 18 noble gases.

Important points at a glance

📜 History & Civics — Social Science I

Topic	Must know
Stone ages	Palaeolithic (rough tools) → Mesolithic (microliths) → Neolithic (polished tools, agriculture). "Neolithic Revolution" coined by Gordon Childe. Agriculture began in the Fertile Crescent.
Harappan cities	Harappa, Mohenjodaro, Lothal — grid streets, covered drainage, granaries, standardised bricks and weights.
6th century BCE	Age of new ideas: Buddha and Mahavira in India, Confucius in China, Pythagoras in Greece.
Buddhism	Three Jewels = right faith, right knowledge, right action. Taught in Pali. Sects: Mahayana, Hinayana. Stupas hold his relics.
Jainism	Mahavira, born at Kundagrama near Vaishali. Core = ahimsa. 24 Tirthankaras. Sects: Swetambara, Digambara.
Magadha	Rose because of fertile land, iron ore, elephants, the Ganga. Rulers: Bimbisara, Ajatashatru. One of the 16 Mahajanapadas.
Mauryan Empire	~322–185 BCE. Founder Chandragupta Maurya, adviser Kautilya. Capital Pataliputra (Ujjayini was only provincial). Greatest ruler Ashoka.
Arthashastra	By Kautilya. Saptanga = Swami, Amatya, Janapada, Durga, Kosha, Danda, Mitra.
Ashoka's Dhamma	Tolerance, respect for elders and teachers, compassion for the sick and enslaved, non-violence. Spread by rock and pillar edicts.
Athens	Direct assembly voting, but citizens = free males over 30 only. Women, slaves, foreigners excluded.
Seventh Schedule	Union (defence, railways, foreign affairs) · State (police, agriculture, jails) · Concurrent (education, forests — central law prevails).
Lok Sabha	543 members · directly elected · 5-year term · minimum age 25 · Speaker presides.
Rajya Sabha	Upper House · minimum age 30 · elected by state assemblies · 6-year terms.
Federalism	Division of powers · written Constitution supreme · independent judiciary · bicameral legislature · single citizenship.

🗺️ Geography & Economics — Social Science II

Topic	Must know
Three ranges	Himadri (~6,100 m) → Himachal (3,500–4,500 m) → Shiwalik (60–150 km wide).
Trans-Himalaya	Karakoram, Ladakh, Zaskar — north of the main Himalaya. K2 is India's highest peak.
Eastern hills	Patkai Bum, Naga, Mizo, Garo, Khasi, Jaintia.
W–E divisions	Western (Indus → Kali/Sutlej) · Central (Kali → Teesta) · Eastern (Teesta → Brahmaputra).
Local terms	Bugyals = alpine meadows · Karewas = Kashmir lake terraces, saffron · Duns = valleys between Himachal and Shiwalik.
Passes	Banihal, Rohtang, Baralacha La.
River origins	Indus — near Mansarovar · Ganga — Gangotri · Yamuna — Yamunotri · Brahmaputra — Chemayungdung. All perennial.
Tourism phases	Pilgrimage → colonial hill stations (19th c.) → adventure tourism after Everest 1953.
Northern plains	~3,200 km long, largest alluvial plain in the world. Alluvium 1,000–2,000 m deep.
The belts	Bhabar (8–10 km, pebbles, rivers underground) → Tarai (10–20 km, marshy) → Bhangar (old) / Khadar (new, fertile).
Doabs	Land between two converging rivers — Bari Doab (Beas–Ravi), Rachna Doab (Ravi–Chenab).
Factors of production	Land → Rent · Labour → Wage · Capital → Interest · Entrepreneurship → Profit.
Human capital	Built by education, healthcare, training, migration, information. Blocked by poverty.
Unemployment	Open · Seasonal · Disguised · Structural — classify by what caused it.

1 · 🗺️ India — the map-marking question

Geography Ch 1 · the SCERT model paper has a 4-mark map question on exactly these features

How to place them: the three main ranges run north-west to south-east in parallel arcs across the top. Himadri is innermost (northernmost), then Himachal, then Shiwalik closest to the plains. Karakoram sits beyond Himadri in the far north-west (Ladakh side), and the Naga Hills are in the far north-east near the Myanmar border. Learn the order inward-to-outward and the map question answers itself.

2 · 🗺️ Himalayas — north–south cross-section

Geography Ch 1 · the picture behind the range, height, Dun and Bugyal questions

What to say: the three ranges lie parallel and get lower southwards — Himadri is permanently snow-capped, Himachal is the middle band where most hill stations sit, and Shiwalik is the low outer range meeting the plains. Duns are the flat valleys between Himachal and Shiwalik. Bugyals are alpine meadows above the tree line, and Karewas are the humus-rich lake terraces of the Kashmir valley where saffron is grown.

3 · 🗺️ Northern plains — the belts and the vanishing river

Geography Ch 2 · answers Bhabar, Tarai, Bhangar, Khadar and the alluvial fan in one picture

The mechanism to state: a river leaving the mountains loses slope, so it loses velocity and drops its load — coarsest first. That builds the alluvial fan and sorts the plain into belts. The Bhabar is so porous the river sinks into it; it re-emerges in the Tarai as marsh. Beyond that lies the true alluvial plain: Bhangar above flood level (older, less fertile, kankar nodules) and Khadar on the floodplain (newer, resilted every flood, highly fertile).

4 · 📜 History timeline — where everything sits

History Ch 1–2 · stops you confusing Mahajanapadas with the Mauryan Empire

The confusion this fixes: Mahajanapadas are the 16 states of the 6th century BCE; Magadha was one of them. The Mauryan Empire came after, absorbing them. So Bimbisara and Ajatashatru are Magadha kings, while Chandragupta and Ashoka are Mauryan emperors — a favourite trap in matching questions.

5 · 📜 How the Constitution divides power — two different splits

Civics Ch 4 · federalism is vertical, separation of powers is horizontal

Don't mix these up — exams ask about both, sometimes in the same paper. Federalism divides power between levels of government. Separation of powers divides it between organs of government. The Union List exists because some things must be uniform nationwide; the State List because some things need local knowledge; the Concurrent List because some things genuinely belong to both.

6 · 🗺️ Factors of production and human capital

Economics Ch 4 · the matching question appeared in both real years and the model paper

Why this is worth a diagram: the four-pair matching question appeared in both real years and the SCERT model paper — it is the single most repeated Social Science item found. Then the follow-up: spending on education and healthcare upgrades people the way a machine upgrade upgrades a factory, so it counts as investment, not consumption. That is what makes people "capital".

1 · Chloroplast — grana and stroma

Ch 1 · a 3-mark structure question in the SCERT model paper

What to say: the grana are stacks of disc-shaped thylakoids holding the chlorophyll — this is where light is trapped and water is split (photolysis), releasing oxygen. The stroma is the surrounding fluid, where the energy from the light phase is used to convert CO₂ into glucose. The grana supply the energy; the stroma spends it.

2 · Villus — how absorption actually works

Ch 2 · the capillary/lacteal split is the marking point

Two things earn marks: villi are finger-like projections that hugely increase the surface area for absorption; and each villus has two absorptive routes — the blood capillaries take glucose and amino acids to the hepatic portal vein and the liver, while the lacteal takes fats into the lymphatic system, bypassing the liver at first.

3 · The heart — two sides, two circuits

Ch 2 · the 4-mark question in the SCERT model paper

The design logic: the right side handles deoxygenated blood (body → lungs, pulmonary circulation) and the left handles oxygenated blood (lungs → body, systemic circulation). The septum keeps them separate so tissues get fully oxygenated blood. The left ventricle's wall is thicker because it must pump to the whole body, not just next door to the lungs.
The catch examiners love: the pulmonary artery carries deoxygenated blood and the pulmonary vein carries oxygenated blood — because artery and vein are named by direction relative to the heart, not by oxygen content.

4 · Tooth structure

Ch 2 · a 3-mark "redraw and label" question in the SCERT model paper

Four layers, outside in: enamel (hardest non-living substance in the body), dentine (bone-like, contains calcium, forms the bulk), pulp cavity (nerves and blood vessels — this is what hurts in a cavity), and cementum covering the root and anchoring the tooth in the jaw. The exam version asks you to identify "the hard non-living part" (enamel) and "the connective tissue containing calcium" (dentine).