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CBSE Class X – Science Practice Question Paper
Academic Session: 2026–2027
Set – 3
CBSE-pattern practice paper • Not an official CBSE question paper
General Instructions:
- This question paper consists of 39 questions in three sections: Section A – Biology, Section B – Chemistry and Section C – Physics.
- All questions are compulsory. However, an internal choice is provided in some questions. Attempt only one alternative in such questions.
- Questions carry 1, 2, 3, 4 and 5 marks as indicated.
- Read each question carefully before answering.
- Use appropriate scientific terminology and balanced chemical equations wherever required.
- Draw neat and properly labelled diagrams wherever asked.
- Calculators are not permitted unless specifically allowed by the examination authority.
Section A – Biology
Q1. Which of the following organisms obtains nutrition from another living organism without immediately killing it?
[1]
Q2. Which part of the human digestive system is mainly responsible for the absorption of digested nutrients?
[1]
Q3. The movement of a plant shoot towards light is an example of:
[1]
Q4. Which hormone is secreted by the pancreas and helps maintain blood glucose level?
[1]
Q5. In a monohybrid cross, the phenotypic ratio generally observed in the F₂ generation is:
[1]
Q6. Which of the following is most likely to undergo biomagnification in a food chain?
[1]
Directions for Q7 and Q8: Choose the correct option:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Q7.
Assertion (A): The small intestine is highly efficient in absorbing digested food.
Reason (R): Its inner lining contains numerous finger-like projections called villi. [1]
Reason (R): Its inner lining contains numerous finger-like projections called villi. [1]
Q8.
Assertion (A): Asexual reproduction generally produces offspring that are genetically similar to the parent.
Reason (R): Asexual reproduction usually involves a single parent and does not involve fusion of gametes. [1]
Reason (R): Asexual reproduction usually involves a single parent and does not involve fusion of gametes. [1]
Q9.
Differentiate between aerobic and anaerobic respiration on the basis of oxygen requirement and products formed.
[2]
Q10.
Why are alveoli in the lungs numerous and surrounded by a network of blood capillaries? Give two reasons.
[2]
Q11.
(a) What is a reflex action?
(b) Explain the role of the spinal cord in a reflex action.
(c) Why is a reflex action usually faster than a conscious response? [3]
(b) Explain the role of the spinal cord in a reflex action.
(c) Why is a reflex action usually faster than a conscious response? [3]
Q12.
Explain how water is transported from roots to the leaves of a tall plant. Mention the role of xylem and transpiration pull.
[3]
Q13.
Explain the inheritance of sex in human beings using a simple cross. Why is the probability of a male or female child approximately equal?
[3]
Q14. Read the following passage and answer the questions:[4]
The nervous system and endocrine system coordinate different activities in the human body. The nervous system uses electrical impulses and chemical signals to transmit information rapidly. Endocrine glands release hormones into the bloodstream. Hormonal effects are generally slower but may continue for a longer period. During stressful situations, the adrenal glands release adrenaline, which prepares the body for immediate action.
(a) Name the hormone released during emergency situations.
[1]
(b) Name the gland that secretes this hormone. [1]
(c) State two changes that occur in the body under the influence of adrenaline. [2]
(b) Name the gland that secretes this hormone. [1]
(c) State two changes that occur in the body under the influence of adrenaline. [2]
OR
(c) Differentiate between nervous control and hormonal control with respect to speed and duration of effect.
[2]
Q15.
(a) Draw a neat labelled diagram of a nephron.
(b) Explain ultrafiltration and selective reabsorption during urine formation.
(c) Why is selective reabsorption important? [5]
(b) Explain ultrafiltration and selective reabsorption during urine formation.
(c) Why is selective reabsorption important? [5]
OR
(a) Explain the process of pollination.
(b) Differentiate between self-pollination and cross-pollination.
(c) State two advantages of sexual reproduction in flowering plants. [5]
(b) Differentiate between self-pollination and cross-pollination.
(c) State two advantages of sexual reproduction in flowering plants. [5]
Section B – Chemistry
Q16.
Which gas is evolved when dilute hydrochloric acid reacts with sodium carbonate?
[1]
Q17.
A solution having pH 2 is:
[1]
Q18.
Which metal is stored under kerosene because it reacts vigorously with air and moisture?
[1]
Q19.
Which functional group is present in ethanol?
[1]
Q20.
Which of the following represents a displacement reaction?
[1]
Q21.
Assertion (A): Ionic compounds generally have high melting points.
Reason (R): Strong electrostatic forces exist between oppositely charged ions in an ionic compound. [1]
Reason (R): Strong electrostatic forces exist between oppositely charged ions in an ionic compound. [1]
Q22.
Write the chemical equation for the reaction of zinc with dilute sulphuric acid. Name the gas evolved and state one test for this gas.
[2]
Q23.
A metal X is obtained from its oxide by reduction with carbon. The metal lies below carbon in the reactivity series.
(a) What is meant by reduction?
(b) Why can carbon be used for extracting X?
(c) Give one example of a metal that can be extracted by this method. [3]
(a) What is meant by reduction?
(b) Why can carbon be used for extracting X?
(c) Give one example of a metal that can be extracted by this method. [3]
OR
Differentiate between ionic and covalent compounds on the basis of:
(i) formation,
(ii) melting point,
(iii) electrical conductivity. [3]
(i) formation,
(ii) melting point,
(iii) electrical conductivity. [3]
Q24.
Explain why carbon forms a very large number of compounds. Describe catenation and tetravalency with suitable examples.
[3]
Q25.
Read the following passage and answer the questions:[4]
Acids and bases have several important applications in everyday life. Hydrochloric acid is present in the stomach and assists digestion. Sodium hydrogen carbonate is used in baking and as an antacid. Bleaching powder is used for disinfecting drinking water. Plaster of Paris is used for making casts and moulds.
(a) What is the role of hydrochloric acid in the stomach?
[1]
(b) Write the chemical formula of baking soda. [1]
(c) Give one use each of bleaching powder and Plaster of Paris. [2]
(b) Write the chemical formula of baking soda. [1]
(c) Give one use each of bleaching powder and Plaster of Paris. [2]
OR
(c) Write the chemical formula of Plaster of Paris and state what happens when it is mixed with water.
[2]
Q26.
(a) Explain the cleansing action of soap.
(b) Why does soap not work efficiently in hard water?
(c) State one advantage of detergents over soaps. [5]
(b) Why does soap not work efficiently in hard water?
(c) State one advantage of detergents over soaps. [5]
OR
(a) What is esterification?
(b) Write the chemical equation for the reaction between ethanol and ethanoic acid.
(c) State two properties of ethanoic acid. [5]
(b) Write the chemical equation for the reaction between ethanol and ethanoic acid.
(c) State two properties of ethanoic acid. [5]
Q27.
Complete and balance the following equations:
(a) Na₂CO₃ + HCl → ______ + ______ + ______
(b) CuO + H₂ → ______ + ______ [2]
(a) Na₂CO₃ + HCl → ______ + ______ + ______
(b) CuO + H₂ → ______ + ______ [2]
Section C – Physics
Q28.
An object placed beyond the centre of curvature of a concave mirror forms an image that is:
[1]
Q29.
The SI unit of electric resistance is:
[1]
Q30.
If the length of a wire is doubled while its area of cross-section remains unchanged, its resistance becomes:
[1]
Q31.
The direction of magnetic field around a straight current-carrying conductor can be determined by:
[1]
Q32.
Assertion (A): Domestic electrical appliances are connected in parallel.
Reason (R): Each appliance receives the same potential difference as the mains supply. [1]
Reason (R): Each appliance receives the same potential difference as the mains supply. [1]
Q33.
Assertion (A): A convex lens can form a real image.
Reason (R): A convex lens converges parallel rays of light towards its principal focus. [1]
Reason (R): A convex lens converges parallel rays of light towards its principal focus. [1]
Q34.
An object is placed 20 cm in front of a convex lens of focal length 10 cm.
Find the position and nature of the image formed.
[2]
Q35.
State Ohm’s law. Write its mathematical expression and explain the meaning of each symbol.
[2]
OR
Two resistors of 4 Ω and 6 Ω are connected in series. Calculate their equivalent resistance.
[2]
Q36.
(a) Why does the sky appear blue during the day?
(b) Why does the sun appear reddish at sunrise and sunset? [3]
(b) Why does the sun appear reddish at sunrise and sunset? [3]
Q37.
A 12 V battery is connected to a resistor of 6 Ω.
(a) Calculate the current flowing through the resistor.
(b) Calculate the electrical power consumed.
(c) Calculate the electrical energy consumed in 5 minutes in joules. [3]
(a) Calculate the current flowing through the resistor.
(b) Calculate the electrical power consumed.
(c) Calculate the electrical energy consumed in 5 minutes in joules. [3]
Q38.
Read the following passage and answer the questions:[4]
Electrical energy is widely used in homes for lighting, heating, cooling and operating appliances. The power of an electrical appliance is the rate at which it consumes electrical energy. Household appliances are generally connected in parallel so that each appliance can operate independently.
(a) Write the formula for electric power in terms of voltage and current.
[1]
(b) An appliance consumes 1000 W at 250 V. Calculate the current drawn. [1]
(c) Why are household circuits connected in parallel? Give two reasons. [2]
(b) An appliance consumes 1000 W at 250 V. Calculate the current drawn. [1]
(c) Why are household circuits connected in parallel? Give two reasons. [2]
OR
(c) A 2 kW heater operates for 3 hours. Calculate the electrical energy consumed in kWh.
[2]
Q39.(a) An object is placed 30 cm in front of a concave mirror of focal length 15 cm.
Calculate the image distance and magnification.
(b) Draw a neat ray diagram for the situation.
(c) State the nature of the image. [5]
(b) Draw a neat ray diagram for the situation.
(c) State the nature of the image. [5]
OR
(a) State Fleming’s Left-Hand Rule.
(b) Describe an experiment to show that a current-carrying conductor experiences a force in a magnetic field.
(c) State two factors affecting the magnitude of this force. [5]
(b) Describe an experiment to show that a current-carrying conductor experiences a force in a magnetic field.
(c) State two factors affecting the magnitude of this force. [5]
ADEPT YOURSELF
Set 3 – Answer Key & Marking Scheme
Class X Science • 2026–2027
Section A – Biology
| Q. | Expected Answer / Value Points | Marks |
|---|---|---|
| 1 | (b) Cuscuta | 1 |
| 2 | (c) Small intestine | 1 |
| 3 | (c) Phototropism | 1 |
| 4 | (b) Insulin | 1 |
| 5 | (c) 3 : 1 | 1 |
| 6 | (c) DDT | 1 |
| 7 | (a) Both A and R are true and R is the correct explanation. | 1 |
| 8 | (a) Both A and R are true and R is the correct explanation. | 1 |
| 9 | Aerobic respiration requires oxygen and generally produces carbon dioxide, water and energy. Anaerobic respiration occurs without oxygen and may produce lactic acid in muscles or alcohol and carbon dioxide in yeast. | 2 |
| 10 | Alveoli provide a very large surface area for gaseous exchange and their thin walls and rich capillary network allow rapid diffusion of oxygen and carbon dioxide. | 2 |
| 11 | Reflex action is a rapid, automatic response to a stimulus. The spinal cord coordinates the reflex pathway. It is faster because the immediate response does not require the brain to first process the stimulus consciously. | 3 |
| 12 | Water enters roots and moves through xylem vessels. Transpiration from leaves creates a suction force called transpiration pull, which helps draw water upward through the xylem. | 3 |
| 13 | Female = XX and male = XY. Ova carry only X, while sperm carry either X or Y. X sperm + X ovum produces XX female; Y sperm + X ovum produces XY male. Therefore probability is approximately equal. | 3 |
| 14 | (a) Adrenaline. (b) Adrenal gland. (c) Heart rate increases and blood flow to skeletal muscles increases; breathing rate may also increase. | 4 |
| 15 | Nephron diagram with appropriate labels; ultrafiltration occurs in the glomerulus; useful substances are selectively reabsorbed mainly in the renal tubule. Reabsorption prevents excessive loss of water, glucose and useful salts. | 5 |
Section B – Chemistry
| Q. | Expected Answer / Value Points | Marks |
|---|---|---|
| 16 | (c) Carbon dioxide | 1 |
| 17 | (a) Strongly acidic | 1 |
| 18 | (b) Sodium | 1 |
| 19 | (c) –OH | 1 |
| 20 | (b) Zn + CuSO₄ → ZnSO₄ + Cu | 1 |
| 21 | (a) Both A and R are true and R is the correct explanation. | 1 |
| 22 | Zn + H₂SO₄ → ZnSO₄ + H₂. Gas: hydrogen. It burns with a characteristic pop sound. | 2 |
| 23 | Reduction means removal of oxygen or gain of electrons. Carbon can reduce oxides of metals less reactive than carbon. Example: zinc extraction from zinc oxide. | 3 |
| 24 | Catenation is carbon’s ability to form bonds with other carbon atoms, producing chains and rings. Tetravalency means carbon forms four covalent bonds because it has four valence electrons. | 3 |
| 25 | (a) HCl provides acidic medium and helps digestion. (b) NaHCO₃. (c) Bleaching powder disinfects water; Plaster of Paris is used for casts/moulds. | 4 |
| 26 | Soap molecules have hydrophilic and hydrophobic parts and form micelles around oily dirt. Hard water produces insoluble scum with calcium and magnesium ions. Detergents generally work effectively in hard water. | 5 |
| 27 | (a) Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂ (b) CuO + H₂ → Cu + H₂O | 2 |
Section C – Physics
| Q. | Expected Answer / Value Points | Marks |
|---|---|---|
| 28 | (b) Real, inverted and diminished | 1 |
| 29 | (c) Ohm | 1 |
| 30 | (c) 2R | 1 |
| 31 | (b) Right-Hand Thumb Rule | 1 |
| 32 | (a) Both A and R are true and R is the correct explanation. | 1 |
| 33 | (a) Both A and R are true and R is the correct explanation. | 1 |
| 34 | Using lens formula: 1/f = 1/v – 1/u. With f = +10 cm and u = –20 cm, v = +20 cm. Image is real and inverted, formed at 20 cm on the other side. | 2 |
| 35 | Ohm’s law: At constant temperature, current through a conductor is directly proportional to potential difference. V = IR, where V is voltage, I is current and R is resistance. | 2 |
| 36 | Blue light is scattered more strongly by atmospheric particles, making the sky appear blue. At sunrise and sunset sunlight travels a longer distance through the atmosphere; shorter wavelengths are scattered away and red light reaches the observer more strongly. | 3 |
| 37 | I = V/R = 12/6 = 2 A. P = VI = 12 × 2 = 24 W. Energy = Pt = 24 × 300 = 7200 J. | 3 |
| 38 | (a) P = VI. (b) I = P/V = 1000/250 = 4 A. (c) Parallel connection allows independent operation and gives each appliance the same mains potential difference. | 4 |
| 39 | For concave mirror: f = –15 cm, u = –30 cm. Using mirror formula, v = –30 cm. Magnification m = –1. Image is real, inverted and same size. Appropriate ray diagram required. | 5 |