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Class 9 Science important questions chapter-wise 2026-27, with answers

CMDLearn · 5 November 2026

These are 26 important questions for Class 9 Science in 2026-27, two from each of the 13 chapters of the new NCERT book, Exploration. Each question carries a marks label (1, 2 or 3) and a worked answer, and each chapter heading gives the book's printed pages.

The questions are our own. None is a question or worked example from the book, and none copies the numbers of our chapter guides, so you can use them as fresh practice before the half-yearly exam. A teacher has not yet reviewed them.

What CBSE has published for Class 9 Science in 2026-27

For 2026-27, the book is new. Exploration replaces the old Class 9 Science textbook, and its 13 chapters are listed on its contents page (iesc1ps, PDF page 19). If you learnt the old chapter names, this page maps them to the new book.

CBSE's Class IX Science (086) curriculum for 2026-27 gives the annual theory paper 80 marks, in four units, and lists the chapters of each unit by number (course structure, PDF page 4):

Two things to know about this table:

• Chapter 1, Exploration: Entering the World of Secondary Science, is in the book but not in any of CBSE's four units. Ask your teacher whether your school's papers test it.
• CBSE gives marks per unit, never per chapter.

CBSE also lists an optional course, Science at Advanced Level, for Grade 9 in a file of its own. This page follows the main Science course.

The paper is 3 hours. Another 20 marks are internal assessment: periodic assessment (5), multiple assessment (5), portfolio (5) and practical work (5), for a total of 100 (PDF page 4).

Class 9 has no board exam: your school sets the half-yearly and annual papers. So the 1, 2 and 3-mark labels below are our guide to how much working each answer needs, not CBSE's labels. Ask your teacher which chapters your half-yearly paper covers.

The questions, chapter by chapter

1. Exploration: Entering the World of Secondary Science (Chapter 1, printed pages 1 to 7)

Q1 (1 mark, multiple choice). Which statement explains why something happens, the way a scientific theory does?

(A) A metal rod gets longer every time it is heated. (B) A heated rod gets longer because its particles vibrate more and move slightly further apart. (C) This rod is 1.2 m long. (D) I think the rod will melt.

Answer: (B). (A) only describes a pattern that repeats, which is what a law does. (B) gives the reason behind the pattern, which is what a theory does. (C) is a measurement, and (D) is a guess with no evidence.

Q2 (2 marks, short answer). You want a simple model for how long a stone takes to fall from a first-floor balcony to the ground. Name two details you would keep and two you would ignore. Why does ignoring details help?

Answer:

• Keep: the height of the balcony, and the fact that gravity pulls the stone down (the stone starts from rest).
• Ignore: the colour of the stone, and who drops it. For a small, heavy stone falling a few metres, air resistance is also small enough to ignore.
• Ignoring details that do not change the answer keeps the model simple enough to work out, while still giving a useful prediction.

2. Cell: The Building Block of Life (Chapter 2, printed pages 8 to 27)

Q3 (1 mark, multiple choice). Cucumber slices left in a strong salt solution go soft and limp. This happens because:

(A) salt enters the cells and breaks the cell walls (B) water moves out of the cells by osmosis (C) the cells divide by mitosis (D) the cell membrane dissolves

Answer: (B). The salt solution outside has less water than the cell sap inside, so water diffuses out of the cells across the selectively permeable cell membrane. That movement of water across a membrane is osmosis.

Q4 (3 marks, short answer). A student sees a cell under the microscope with a cell wall, green chloroplasts and one large central vacuole. (a) Is it from a plant or an animal? (b) What is the cell wall made of in plants, and what does it do? (c) Which organelle is called the powerhouse of the cell, and why?

Answer:

• (a) A plant. A cell wall, chloroplasts and a large central vacuole are features of plant cells.
• (b) The plant cell wall is made mainly of cellulose. It is a rigid outer covering that gives the cell shape and support and protects it.
• (c) The mitochondria. They release energy from food for the cell's work.

3. Tissues in Action (Chapter 3, printed pages 28 to 47)

Q5 (1 mark, multiple choice). A lawn is mowed on Sunday, and by Friday the grass is tall again. The tissue that makes this regrowth possible is:

(A) apical meristem (B) lateral meristem (C) intercalary meristem (D) phloem

Answer: (C). Intercalary meristem is found at the nodes of the stem (at the base of an internode, just above a node). Its cells keep dividing after the top is cut, which is why grass grows back after being mowed or grazed.

Q6 (3 marks, short answer). (a) What does a tendon join, and what does a ligament join? (b) Name the type of joint at the shoulder and at the elbow, and say how their movements differ.

Answer:

• (a) A tendon joins a muscle to a bone. A ligament joins a bone to another bone at a joint.
• (b) The shoulder is a ball and socket joint: the arm can move freely in many directions. The elbow is a hinge joint: it can only bend and straighten, much as a door swings on its hinges.

4. Describing Motion Around Us (Chapter 4, printed pages 48 to 71)

Q7 (2 marks, numerical). Riya walks 300 m east along a straight road, then turns and walks 100 m west. The whole walk takes 200 s. Find (a) the distance travelled and the displacement, (b) her average speed and average velocity.

Answer: (a) distance = 400 m, displacement = 200 m east; (b) average speed = 2 m/s, average velocity = 1 m/s east.

• Distance adds the two parts: 300 + 100 = 400 m. Displacement is the change in position: 300 − 100 = 200 m east.
• Average speed = 400 ÷ 200 = 2 m/s. Average velocity = 200 ÷ 200 = 1 m/s, towards the east.

Q8 (3 marks, numerical). A scooter starts from rest and speeds up uniformly at 1.5 m/s² for 8 s along a straight road. Find its velocity after 8 s and the distance it covers. Check your distance with v² = u² + 2as.

Answer: v = 12 m/s, s = 48 m.

• u = 0, a = 1.5 m/s², t = 8 s.
• v = u + at = 0 + 1.5 × 8 = 12 m/s.
• s = ut + ½at² = 0 + ½ × 1.5 × 64 = 48 m.
• Check: u² + 2as = 0 + 2 × 1.5 × 48 = 144 = 12² ✓.

5. Exploring Mixtures and their Separation (Chapter 5, printed pages 72 to 93)

Q9 (3 marks, numerical). 24 g of sugar is dissolved in 136 g of water. (a) Find the concentration of the solution as a mass by mass percentage. (b) How much more sugar must be dissolved in it to make the solution 20% by mass?

Answer: (a) 15%; (b) 10 g more sugar.

• (a) Mass of solution = 24 + 136 = 160 g. Mass by mass percentage = 24 ÷ 160 × 100 = 15%.
• (b) Add x g of sugar: (24 + x) ÷ (160 + x) = 20/100. So 100(24 + x) = 20(160 + x), which gives 2400 + 100x = 3200 + 20x, so 80x = 800 and x = 10 g.
• Check: 34 ÷ 170 × 100 = 20% ✓.

Q10 (2 marks, short answer). Name a method to separate each: (a) common salt from sea water; (b) kerosene from water; (c) the coloured dyes in a drop of black sketch-pen ink.

Answer:

• (a) Evaporation, then crystallization: the water leaves and salt crystals stay behind.
• (b) A separating funnel: kerosene and water are immiscible and form two layers, and the lower water layer is run off through the tap.
• (c) Paper chromatography: the dyes travel different distances up the paper and separate into bands.

6. How Forces Affect Motion (Chapter 6, printed pages 94 to 115)

Q11 (2 marks, numerical). A 60 kg wooden crate is pushed with a force of 150 N along a level floor, and friction acts on it with a force of 30 N. Find the net force and the crate's acceleration.

Answer: net force = 120 N; a = 2 m/s².

• The forces are unbalanced: net force = 150 − 30 = 120 N in the direction of the push.
• Newton's second law, F = ma: a = 120 ÷ 60 = 2 m/s².

Q12 (3 marks, short answer). Two skaters stand still on smooth ice, facing each other: Arjun (50 kg) and Meera (40 kg). Arjun pushes Meera with a force of 80 N. (a) What force does Meera exert on Arjun? Which law tells you? (b) Find the acceleration of each skater during the push. (c) Why do they move apart in opposite directions?

Answer:

• (a) 80 N on Arjun, in the opposite direction. Newton's third law: forces between two objects come in pairs, equal in size and opposite in direction, acting on different objects.
• (b) Arjun: a = 80 ÷ 50 = 1.6 m/s². Meera: a = 80 ÷ 40 = 2 m/s². The lighter skater gets the larger acceleration.
• (c) Each skater feels a force pointing away from the other, so each speeds up away from the other.

7. Work, Energy, and Simple Machines (Chapter 7, printed pages 116 to 139)

Q13 (2 marks, numerical). Kabir lifts a 12 kg school bag straight up onto a shelf 1.5 m high in 3 s. Take g = 10 m/s². Find the work he does on the bag and his average power.

Answer: W = 180 J; P = 60 W.

• The force needed equals the bag's weight: mg = 12 × 10 = 120 N.
• W = force × displacement = 120 × 1.5 = 180 J.
• Power = work ÷ time = 180 ÷ 3 = 60 W.

Q14 (3 marks, numerical). A 2 kg flower pot falls from a balcony 5 m above the ground. Take g = 10 m/s² and ignore air resistance. Find (a) its potential energy at the start, (b) its speed just before it hits the ground.

Answer: (a) 100 J; (b) 10 m/s.

• (a) Potential energy = mgh = 2 × 10 × 5 = 100 J.
• (b) Mechanical energy is conserved, so all of it becomes kinetic energy: ½mv² = 100, so ½ × 2 × v² = 100, v² = 100 and v = 10 m/s.

8. Journey Inside the Atom (Chapter 8, printed pages 140 to 161)

Q15 (1 mark, short answer). An element has atomic number 15. Write its electron distribution in the K, L and M shells, and its valency.

Answer: 2, 8, 5; valency 3. The K shell holds 2 and the L shell 8, leaving 5 in the M shell. With 5 valence electrons, the atom gains 3 to complete its octet, so its valency is 3.

Q16 (3 marks, short answer). A neutral atom has mass number 27, and its nucleus has 14 neutrons. (a) Find its atomic number and the number of electrons. (b) Write its electron distribution and valency. (c) Name the element and write the ion it forms.

Answer:

• (a) Atomic number = mass number − neutrons = 27 − 14 = 13. A neutral atom has as many electrons as protons: 13 electrons.
• (b) 2, 8, 3. With 3 valence electrons it loses them to reach an octet, so its valency is 3.
• (c) Atomic number 13 is aluminium (Al). Losing 3 electrons gives the ion Al³⁺.

9. Atomic Foundations of Matter (Chapter 9, printed pages 162 to 183)

Q17 (2 marks, numerical). Find the molecular mass of sulfuric acid, H₂SO₄. Atomic masses: H = 1 u, S = 32 u, O = 16 u.

Answer: 98 u. (2 × 1) + (1 × 32) + (4 × 16) = 2 + 32 + 64 = 98 u.

Q18 (3 marks, short answer). Lithium forms the ion Li⁺ and oxygen forms the oxide ion O²⁻. (a) Write the formula of lithium oxide. (b) Find its formula unit mass (Li = 7 u, O = 16 u). (c) Is it ionic or covalent, and would you expect it to have a high or a low melting point?

Answer:

• (a) The charges must balance: two Li⁺ for one O²⁻, so the formula is Li₂O.
• (b) (2 × 7) + 16 = 30 u.
• (c) Ionic: it is made of ions held by strong attraction between opposite charges, so it has a high melting point.

10. Sound Waves: Characteristics and Applications (Chapter 10, printed pages 184 to 207)

Q19 (2 marks, numerical). A whistle gives a sound of frequency 500 Hz in air, where sound travels at 340 m/s. Find the wavelength and the time period.

Answer: λ = 0.68 m; T = 0.002 s.

• Speed = frequency × wavelength, so λ = 340 ÷ 500 = 0.68 m.
• Time period T = 1 ÷ frequency = 1 ÷ 500 = 0.002 s.

Q20 (3 marks, numerical). Sound travels at 340 m/s in air. (a) A trekker shouts towards a cliff and hears the echo 1.2 s later. How far is the cliff? (b) Would a child clapping 12 m from a hall wall hear a separate echo? Give a reason.

Answer: (a) 204 m; (b) no.

• (a) The sound goes to the cliff and back: total distance = 340 × 1.2 = 408 m, so the cliff is 408 ÷ 2 = 204 m away.
• (b) The echo would travel 24 m, taking 24 ÷ 340 ≈ 0.07 s. The ear needs a gap of at least 0.1 s to hear the echo as a separate sound, so no echo is heard. (At 340 m/s, the wall must be at least 17 m away.)

11. Reproduction: How Life Continues (Chapter 11, printed pages 208 to 227)

Q21 (1 mark, multiple choice). A farmer wants many new rose plants exactly like her best rose bush. Which method should she use?

(A) Sowing seeds from cross-pollinated flowers (B) Stem cuttings (C) Letting bees pollinate the flowers (D) Waiting for spores

Answer: (B). A stem cutting is vegetative propagation, a form of asexual reproduction, so the new plants are genetically identical to the parent bush. Seeds from cross-pollination mix features from two parents.

Q22 (3 marks, short answer). (a) Give two ways in which sexual reproduction differs from asexual reproduction. (b) Why do offspring from sexual reproduction show variations?

Answer:

• (a) Sexual reproduction usually needs two parents and involves the fusion of reproductive cells (gametes); asexual reproduction needs one parent and no gametes. Asexual offspring are almost exact copies of the parent; sexual offspring are not.
• (b) Gametes are made by meiosis, which mixes the genetic material, so each gamete is different. At fertilisation, a gamete from each parent fuses, so the offspring gets a new combination of features from both. This creates variation.

12. Patterns in Life: Diversity and Classification (Chapter 12, printed pages 228 to 251)

Q23 (2 marks, short answer). The house cat is Felis catus and the jungle cat is Felis chaus. (a) Which word in each name is the genus, and which the species? (b) Are the two cats in the same genus? Are they the same species?

Answer:

• (a) In the binomial system the first word, Felis, is the genus, and the second word (catus, chaus) is the species.
• (b) Same genus (both are Felis), so they are closely related. Different species, because the second words differ.

Q24 (3 marks, short answer). Place each in its kingdom in the five kingdom classification, with one reason: (a) a mushroom, (b) Amoeba, (c) a neem tree, (d) a bacterium.

Answer:

• (a) Fungi: multicellular, with a cell wall, and it cannot make its own food (heterotrophic).
• (b) Protista: a single cell with a true nucleus (unicellular eukaryote).
• (c) Plantae: multicellular, with a cell wall, and it makes its own food (autotrophic).
• (d) Monera: a single cell without a true nucleus.

13. Earth as a System (Chapter 13, from printed page 252)

Q25 (1 mark, multiple choice). On a sunny afternoon in a hill valley, the local wind blows:

(A) from the valley up the warm slopes (B) from the slopes down into the valley (C) only at night (D) from the sea to the land

Answer: (A). By day the sunlit slopes heat up faster, the warm air over them rises, and cooler valley air moves up the slopes to replace it: a valley breeze. At night the flow reverses (mountain breeze).

Q26 (3 marks, short answer). Air is about 78% nitrogen, yet plants cannot use nitrogen gas directly. (a) Give two natural ways in which nitrogen gas is fixed into a form plants can use. (b) How does nitrogen get from plants to animals?

Answer:

• (a) Nitrogen-fixing bacteria, for example Rhizobium, which lives in nodules on the roots of legumes such as pea and gram, and lightning, which turns a small amount of nitrogen into nitrogen oxides that reach the soil with rain.
• (b) Plants use the fixed nitrogen to build proteins, and animals get nitrogen by eating plants (or other animals that ate plants).

How to use these questions

• After each chapter: do its two questions with the book closed, then check your working against the answer, step by step, not just the final number.
• Before the half-yearly or annual paper: do all 26 in two sittings of about 45 minutes each, and mark the ones you got wrong. Go back to that chapter's guide for more practice.
• Show the working and the unit. In numerical questions most of the marks are for the formula, the substitution and the unit at the end (m/s, J, W, u).

More practice, chapter by chapter, with eight questions each: Exploration, Cell, Tissues in Action, Describing Motion, Mixtures and their Separation, How Forces Affect Motion, Work, Energy and Simple Machines, Journey Inside the Atom, Atomic Foundations of Matter, Sound Waves, Reproduction, Diversity and Classification, Earth as a System. Studying in Hindi? Chapter 1, Exploration, in Hindi. The Maths twin of this page: Class 9 Maths important questions 2026-27.

Where CMDLearn fits

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Sources

All checked on 5 November 2026.

• NCERT, Exploration, Textbook of Science for Grade 9, Chapters 1 to 13: ncert.nic.in/textbook/pdf/iesc101.pdf to iesc113.pdf, and the contents page: iesc1ps.pdf
• CBSE, Science (086), Class IX 2026-27, course structure and internal assessment (PDF page 4): cbseacademic.nic.in, ScienceSt_SecP1_2026-27.pdf; the list of 2026-27 subject files: cbseacademic.nic.in/curriculum_2027.html

Definitions, laws and page numbers are from the documents above. Every question and answer on this page is our own, and every number is checked by a script.

Practise this class: Class 9 worksheets, chapter by chapter · free practice, marked instantly · timed revision papers