Question Paper — CBSE Class 10 Science Chapter 5 Notes

CBSE Class 10 Science Sample Paper 2027 – Set 1

Time allowed: 3 hours · Maximum marks: 80

General Instructions

This question paper contains 39 questions. All questions are compulsory.
The question paper is divided into THREE sections: Section A - Biology (30 marks), Section B - Chemistry (25 marks) and Section C - Physics (25 marks).
The question paper has MCQs, VSAs, SAs, LAs and CBQs. Marks are given against each question.
There are Case Based Questions (CBQs) with three sub-questions, of 4 marks each.
Divide your answer sheet into three sections as per the question paper: Section A (Biology), Section B (Chemistry) and Section C (Physics). Answer each question in its own section, and do not mix answers of one section with another.
Instructions are given with each section and question, wherever necessary.
There is no overall choice in the question paper. However, an internal choice has been provided in a few questions. Only one of the choices in such questions must be attempted.

How to use this paper: set a 3-hour timer and write all your answers on paper, just like the board exam. When you finish, take the quiz at the end of this page to score your objective (MCQ) answers instantly, then open the Detailed Solutions and check the rest step by step, with the marks each step carries.

Section A - Biology (30 marks)

Questions 1 to 7 are multiple choice questions and questions 8 and 9 are Assertion-Reason questions, of 1 mark each. Questions 10 to 12 carry 2 marks each, questions 13 and 14 carry 3 marks each, question 15 is a case based question of 4 marks and question 16 is a long answer question of 5 marks.

1. Read the following statements about the breakdown of glucose in living cells.

(i) In yeast, pyruvate is broken down into ethanol and carbon dioxide in the absence of oxygen.
(ii) During a long sprint, pyruvate in the leg muscles is converted into lactic acid when oxygen runs short.
(iii) Anaerobic respiration releases more energy from one molecule of glucose than aerobic respiration.
(iv) The first step, in which glucose is broken down into pyruvate, takes place in the cytoplasm.

Which of these statements are correct?

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

2. Divya kept a potted croton plant with variegated leaves (green with white patches) in a dark room for three days. She then fixed a strip of black paper across one leaf, covering the same part on both sides, and kept the plant in bright sunlight for six hours. Finally she removed the strip, boiled the leaf in alcohol over a water bath, washed it and added iodine solution. In the figure, the shaded parts of the leaf are green: P is a green part, Q is a white patch and R is the green part that was under the strip (dashed outline). Which part(s) of the leaf will turn blue-black?

Variegated leaf with parts P, Q and R; dashed strip across the leaf

(a) P, Q and R
(b) P and R
(c) P only
(d) Q and R

3. Which of the following does NOT happen in a flower after fertilisation?

(a) The ovary grows and ripens into a fruit.
(b) The ovules develop into seeds.
(c) The petals, sepals and stamens may shrivel and fall off.
(d) The style and stigma grow to form the outer covering of the fruit.

4. Consider the following statements about methods used to prevent pregnancy.

(i) Oral pills change the hormonal balance of the body so that eggs are not released.
(ii) A copper-T is placed in the uterus to prevent pregnancy.
(iii) Using a condom prevents sperm from reaching the egg and also protects against sexually transmitted diseases.
(iv) In a vasectomy, the vas deferens is blocked so that the testes stop producing sperm.

Which statements are correct?

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

5. Read the following statements about plant hormones.

(i) Auxin is made at the tip of the shoot; when light falls from one side, it moves towards the shaded side and makes the cells there grow longer.
(ii) Gibberellins help in the growth of the stem.
(iii) Cytokinins promote cell division and are found in higher amounts where cells divide rapidly, as in fruits and seeds.
(iv) Abscisic acid promotes growth and prevents the leaves from wilting.

The correct statements are

(a) (i) and (ii) only
(b) (ii), (iii) and (iv)
(c) (i), (ii) and (iii)
(d) (i), (iii) and (iv)

6. Meenal's parents already have two daughters. What is the chance that their third child will be a son, and whose gamete decides the sex of the child?

(a) 50 per cent; the mother's egg
(b) 50 per cent; the father's sperm
(c) 100 per cent; the father's sperm
(d) 25 per cent; the father's sperm

7. The eco-club of a school in Pune is setting up a compost pit. Which of the following wastes should the students put into it?

(i) Vegetable and fruit peels
(ii) Polythene bags
(iii) Dry leaves
(iv) Broken glass bottles
(v) Used tea leaves

(a) (i) and (ii)
(b) (ii), (iii) and (iv)
(c) (i), (iv) and (v)
(d) (i), (iii) and (v)

Directions: Questions 8, 9, 24 and 32 each consist of two statements, Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option (a), (b), (c) or (d) given with each.

8. Assertion (A): The daughter cells formed when an Amoeba divides by binary fission are very similar to the parent.

Reason (R): The copying of DNA during reproduction is always perfectly accurate, with no errors.

(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.

9. Assertion (A): Depletion of the ozone layer can lead to more cases of skin cancer in human beings.

Reason (R): The ozone layer shields the surface of the Earth from the ultraviolet radiation of the Sun.

10. Answer the following:

(a) In a small herb, water keeps moving up through the xylem even at night, when the stomata are closed and transpiration is very low. What moves the water up at such times? Explain briefly. (1 mark)

(b) Why do veins have valves while arteries do not? (1 mark)

11. Attempt either option (A) or (B).

(A) A health survey in a hill district of Uttarakhand found many people with a swelling in the front of the neck (goitre). Doctors asked every family to switch to iodised salt. Name the gland that is affected and the hormone it makes. What does this hormone do in the body, and how does iodised salt help? (2 marks)

(B) A 12-year-old boy is much shorter than other children of his age. His doctor says that one hormone is not being made in enough amount. Name the hormone and the gland that makes it. What is the main job of this hormone?

12. Every month, the inner lining of the uterus becomes thick and spongy, with a rich supply of blood. Why does the uterus prepare itself in this way? What happens to this lining if the egg released is not fertilised? (2 marks)

13. Answer the following:

(a) Draw a neat diagram of a neuron and label any four of these parts: dendrite, cell body, nucleus, axon, nerve ending. (2 marks)

(b) How is the electrical impulse passed on from one neuron to the next? (1 mark)

14. The figure shows a food web in a grassland near Jaipur. The letters stand for: A - grass, B - grasshopper, C - rabbit, D - frog, E - snake, F - hawk. Each arrow points from the organism that is eaten to the organism that eats it.

Food web with six organisms A to F joined by arrows

(a) Write the longest food chain in this web, using the names of the organisms, and state the trophic level of the snake in it. (1 mark)

(b) Suppose the grass in each chain holds 20,000 kJ of energy. Using the 10 per cent law, find the energy that reaches the hawk (i) through the rabbit and (ii) through the longest chain. (1 mark)

(c) A disease wipes out most of the frogs in this area. What will happen to the number of grasshoppers, and then to the grass? Give a reason. (1 mark)

15. Sameer, a Class 10 student from Nashik, grew pea plants for his science project. He crossed a pure-breeding tall plant that had round seeds (TTRR) with a pure-breeding dwarf plant that had wrinkled seeds (ttrr). All the plants of the F1 generation were tall with round seeds. He then let the F1 plants self-pollinate and raised 800 plants of the F2 generation from the seeds he collected.

(a) What does the appearance of the F1 plants tell us about the traits 'tall' and 'round'? (1 mark)

(b) How many of the 800 F2 plants are expected to be dwarf with round seeds? Show how you got the number. (1 mark)

(c) Out of the 800 F2 plants, how many are expected to be tall? How many of these tall plants will be pure-breeding for tallness (TT)? Explain using the cross for height. (2 marks)

(c) Sameer's friend crossed one of the tall F1 plants (Tt) with a dwarf plant (tt). What ratio of tall to dwarf plants is expected among the offspring? Show the cross. (2 marks)

16. Attempt either option (A) or (B).

(A) Rakesh, a Class 10 student in Kota, noticed that after two hours of football on a hot afternoon, with little to drink, he passed only a small amount of dark yellow urine. On a cool day when he drank plenty of water, he passed a large amount of pale urine.

(i) Draw a neat diagram of a nephron and label Bowman's capsule, glomerulus, tubule and collecting duct. In which part is the blood filtered? (3 marks)

(ii) Explain why Rakesh passed less and darker urine on the hot day. What decides how much water is reabsorbed in the kidneys? (2 marks)

(B) Kabir had a lunch of rice, dal and ghee.

(i) Trace the digestion of the starch in the rice, from the mouth until it is absorbed into the blood. Name the juice or enzyme that acts at each stage. (3 marks)

(ii) In a certain person, the gastric glands secrete much less mucus than normal. What problem is this person likely to face, and why? (2 marks)

Section B - Chemistry (25 marks)

Questions 17 to 23 are multiple choice questions and question 24 is an Assertion-Reason question, of 1 mark each. Question 25 carries 2 marks, questions 26 and 27 carry 3 marks each, question 28 is a case based question of 4 marks and question 29 is a long answer question of 5 marks.

17. Aditi placed a clean copper strip in silver nitrate solution. After some time, the solution turned blue and a shiny greyish-white deposit formed on the strip. Consider these statements:

(i) This is a displacement reaction.
(ii) The solution turns blue because copper nitrate is formed.
(iii) Silver is more reactive than copper.
(iv) The deposit on the strip is silver.

Which statements are correct?

(a) (i) and (ii) only
(b) (i), (ii) and (iv)
(c) (ii) and (iii)
(d) (i), (iii) and (iv)

18. After Aarav ate a toffee, the pH of the saliva in his mouth dropped from about 7 to about 5. Which statement correctly explains this and why brushing helps?

(a) Sugar dissolves in saliva to form an acid directly; toothpaste is neutral and simply washes it away.
(b) Tooth enamel is made of calcium phosphate, which starts to corrode when the pH rises above 5.5.
(c) Brushing with plain water alone raises the pH of the mouth well above 7.
(d) Bacteria in the mouth break down sugar into acids; toothpaste is basic and neutralises the extra acid.

19. Which of the following pairs are two successive members of the same homologous series?

(a) $\mathrm{CH_3OH}$ and $\mathrm{C_2H_5OH}$
(b) $\mathrm{C_2H_6}$ and $\mathrm{C_2H_4}$
(c) $\mathrm{C_3H_6}$ and $\mathrm{C_3H_8}$
(d) $\mathrm{HCHO}$ and $\mathrm{CH_3COOH}$

20. Salma put a clean granule of zinc into each of four test tubes containing aqueous solutions of P - copper sulphate, Q - iron(II) sulphate, R - aluminium sulphate and S - magnesium sulphate. In which test tubes will a deposit form on the zinc?

(a) P only
(b) P and Q
(c) P, Q and R
(d) Q, R and S

21. The structural formula of an organic compound is shown. Which option gives its name and the class of compounds it belongs to?

Structural formula of a three-carbon compound containing oxygen

(a) Propanol; alcohol
(b) Propanone; ketone
(c) Propanal; aldehyde
(d) Propanoic acid; carboxylic acid

22. Ishita passed an electric current through water containing a few drops of dilute sulphuric acid, using the set-up shown. After some time, test tube P had collected twice as much gas as test tube Q. Which gas is collected in P, and how can it be tested?

Electrolysis set-up with gas collected in inverted test tubes P and Q

(a) Hydrogen; it burns with a pop sound when a burning splinter is brought near it
(b) Oxygen; it relights a glowing splinter
(c) Hydrogen; it turns lime water milky
(d) Oxygen; it burns with a pop sound when a burning splinter is brought near it

23. Which of the following oxides react with both acids and bases to form salt and water?

(i) $\mathrm{Al_2O_3}$
(ii) $\mathrm{Na_2O}$
(iii) $\mathrm{ZnO}$
(iv) $\mathrm{CuO}$

(a) (i) and (ii)
(b) (ii) and (iv)
(c) (iii) and (iv)
(d) (i) and (iii)

24. Assertion (A): When dilute hydrochloric acid is diluted further with water, the concentration of hydrogen ions per unit volume increases.

Reason (R): On dilution, the same number of hydrogen ions is spread through a larger volume of solution.

25. Answer the following:

(a) Draw the electron dot structure of a nitrogen molecule, $\mathrm{N_2}$ . (Atomic number of nitrogen = 7) (1 mark)

(b) A molecule of nitrogen has a triple bond, but a molecule of oxygen has a double bond. Why? (1 mark)

26. Attempt either option (A) or (B).

(A) Meera added a pinch of sodium hydrogencarbonate to 2 mL of ethanoic acid in a test tube.

(i) What will she observe? (1 mark)

(ii) Write the balanced chemical equation for the reaction. (1 mark)

(iii) Draw a labelled diagram of the set-up she can use to show that the gas given off turns lime water milky. (1 mark)

(B) Answer the following:

(i) What is saponification? (1 mark)

(ii) Ethyl ethanoate is heated with sodium hydroxide solution. Write the chemical equation for the reaction and name the two products formed. (2 marks)

27. Give reasons for the following:

(a) Old copper vessels kept in a temple in Varanasi slowly lose their shine and get a green coating. (1 mark)

(b) Solid sodium chloride does not conduct electricity, but its solution in water does. (1 mark)

(c) A galvanised iron bucket does not rust even when its zinc coating gets scratched in places. (1 mark)

28. Kavya took 10 mL of dilute sodium hydroxide solution in a conical flask and added two drops of phenolphthalein. The solution turned pink. She then added dilute hydrochloric acid from a dropper, a little at a time, swirling the flask after each addition. The pink colour disappeared just when she had added 8 mL of the acid. She added 2 mL more of the acid, and the solution stayed colourless.

(a) Why did the pink colour disappear when 8 mL of the acid had been added? (1 mark)

(b) If Kavya had used methyl orange instead of phenolphthalein, what colour would the solution have been (i) at the start and (ii) after 10 mL of the acid had been added? (1 mark)

(c) Write the balanced chemical equation for the reaction in the flask. What is the pH of the solution at the moment the pink colour just disappears? Give a reason. (2 marks)

(c) Kavya repeats the experiment with 10 mL of a sodium hydroxide solution that is twice as concentrated. How much of the same acid will she need to make the pink colour disappear? Will the flask become warm or cool during the reaction? Give reasons. (2 marks)

29. Attempt either option (A) or (B).

(A)

(i) Three students make these statements about a strip of magnesium ribbon that their teacher burnt in class.

Ishaan: "The ribbon burns with a dazzling white flame and leaves a white powder, which is magnesium oxide."
Pooja: "The ribbon has to be rubbed with sandpaper first, to remove the dull layer of oxide on its surface."
Farhan: "This is a decomposition reaction, because the solid ribbon breaks down into a powder."

Who is correct and who is not? Justify your answer and write the balanced chemical equation for the reaction. (3 marks)

(ii) Rohit wrote the following in his notebook. Identify the error in each and rewrite it correctly.

(I) $\mathrm{Na_2SO_4 + BaCl_2 \rightarrow BaSO_4 + NaCl}$ ; this is a displacement reaction.
(II) $\mathrm{CaO + H_2O \rightarrow Ca(OH)_2}$ ; this is a decomposition reaction in which heat is absorbed. (2 marks)

(B)

(i) Vivek performed three activities:

P: He mixed lead nitrate solution with potassium iodide solution, and a yellow precipitate formed.
Q: He left some white silver chloride in a china dish in sunlight, and it turned grey.
R: He heated some calcium carbonate strongly, and a gas that turns lime water milky was given off.

For each activity, write the balanced chemical equation and name the type of reaction. (3 marks)

(ii) In a blast furnace at a steel plant in Bhilai, iron ore is heated with carbon monoxide: $\mathrm{Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2}$ . Identify the substance oxidised and the substance reduced. Justify your answer in terms of gain or loss of oxygen. (2 marks)

Section C - Physics (25 marks)

Questions 30 and 31 are multiple choice questions and question 32 is an Assertion-Reason question, of 1 mark each. Questions 33 and 34 carry 2 marks each, questions 35 to 37 carry 3 marks each, question 38 is a case based question of 4 marks and question 39 is a long answer question of 5 marks.

30. Nikhil traced the path of a ray of light through a rectangular glass slab in the laboratory. The figure shows the incident ray, the ray inside the slab and four possible emergent rays 1, 2, 3 and 4. Which one correctly shows the emergent ray?

Ray passing through a glass slab with four possible emergent rays

(a) Ray 1
(b) Ray 2
(c) Ray 3
(d) Ray 4

31. Resistors of 2 Ω and 4 Ω are connected to a 12 V battery, first in series and then in parallel. What current does the battery supply in the two cases?

(a) 9 A in series; 2 A in parallel
(b) 6 A in series; 3 A in parallel
(c) 2 A in series; 9 A in parallel
(d) 2 A in series; 3 A in parallel

32. Assertion (A): A person with normal vision can see objects clearly at any distance from about 25 cm to very far away.

Reason (R): The pupil controls the amount of light entering the eye.

33. An object 2 cm tall is placed 16 cm in front of a convex lens of focal length 12 cm.

(a) Draw a ray diagram to show the formation of the image. (1 mark)

(b) Use the lens formula to find the image distance and the height of the image. (1 mark)

34. Attempt either option (A) or (B).

(A) The Verma family in Lucknow uses an electric geyser rated 1.5 kW for 40 minutes every day.

(I) How many joules make one kilowatt hour (1 kWh)? (1 mark)

(II) Find the electrical energy used by the geyser in 30 days, and its cost at ₹ 6 per kWh. (1 mark)

(B) A wire of resistance 8 Ω is stretched uniformly until its length becomes double.

(I) Find the new resistance of the wire. (1 mark)

(II) Does the resistivity of the wire change? Give a reason. (1 mark)

35. A dentist holds a small concave mirror of focal length 4 cm at a distance of 3 cm from a tooth.

(a) Find the position of the image. (1 mark)

(b) Find the magnification, and state the nature of the image. (1 mark)

(c) Why does the dentist not use a convex mirror for this purpose? (1 mark)

36. A long solenoid is connected to a battery through a key, and the key is closed.

(a) Draw the pattern of magnetic field lines in and around the solenoid. Show the direction of the current in the coil and mark the north and south poles. (2 marks)

(b) What does the pattern of field lines inside the solenoid tell you about the magnetic field there? State one use of this. (1 mark)

37. Study the circuit shown. The key K is closed.

Circuit with a battery, a key and three resistors, two between X and Y

(a) Find the total resistance of the circuit and the current drawn from the battery. (2 marks)

(b) Find the potential difference between X and Y, and the current through the 6 Ω resistor. (1 mark)

38. During frequent power cuts in summer, the Mishra family in Patna uses an inverter. Its 12 V battery stores energy and gives direct current (DC). When the mains supply fails, the inverter changes this DC into alternating current (AC) of 220 V and 50 Hz, the same as the mains supply, and feeds it into the house wiring. In the house, the fans, the lights and the fridge are all connected in parallel, and each circuit is protected by an MCB (miniature circuit breaker).

(a) What does '50 Hz' tell us about the alternating current? (1 mark)

(b) State one advantage of AC over DC. (1 mark)

(c) The inverter can supply a current of at most 5 A at 220 V. During a power cut the family runs the fridge (300 W), four fans (75 W each) and five LED bulbs (20 W each). Can they also switch on an electric iron of 750 W? Show your working. (2 marks)

(c) In the kitchen circuit, which is protected by a 10 A MCB, an electric oven of 2 kW and an electric kettle of 1.3 kW are switched on together on the 220 V supply. Find the total current drawn. What will the MCB do, and why? (2 marks)

39. Attempt either option (A) or (B).

(A) Sunita, a Class 10 student in Shimla, reads her textbook easily, but the writing on the blackboard looks blurred from the last bench. Her eye doctor prescribes spectacles of power -0.5 D.

(i) What does the negative sign of the power tell you about the lens? Which defect of vision does Sunita have? (1 mark)

(ii) Find the far point of Sunita's eye. (1 mark)

(iii) Sunita's cousin has the same defect, but his far point is 4 m from his eye. Will he need a lens of greater or smaller power than Sunita? Give a reason. (1 mark)

(iv) Draw a ray diagram to show how Sunita's spectacle lens lets her see a distant object clearly. Mark her far point. (2 marks)

(B) Light is bent as it passes through the Earth's atmosphere and through glass.

(i) We can see the Sun about two minutes before it actually rises above the horizon. Explain why. (1 mark)

(ii) If the Earth had no atmosphere, would a day (sunrise to sunset) be longer or shorter than now? Give a reason. (1 mark)

(iii) Why do stars twinkle? (1 mark)

(iv) Draw a labelled diagram of the arrangement of two identical glass prisms by which the colours of white light can be combined to give white light again. (2 marks)