22 free Science MCQs written in the Class 10 Boards exam pattern, each with a step-by-step solution. Tap an option for instant feedback — no sign-up, no ads.
Revise with smart repetition →✍️ These are original practice questions written in the Class 10 Boards pattern for the Class 10 board exams (CBSE pattern) — not questions from any official past paper.
Q1. The SI unit of electric resistance is the:
C. Ohm — Resistance is measured in ohms (Ω). The volt is potential difference, the ampere is current, and the watt is power.
Q2. The common name of sodium hydrogencarbonate (NaHCO₃) is:
B. Baking soda — NaHCO₃ is baking soda (sodium bicarbonate). Washing soda is Na₂CO₃·10H₂O, common salt is NaCl, and bleaching powder is CaOCl₂.
Q3. The coloured part of the human eye that controls the size of the pupil is the:
C. Iris — The iris is the coloured, muscular diaphragm that adjusts the size of the pupil to control how much light enters. The retina is the light-sensitive screen at the back of the eye.
Q4. The process by which green plants prepare their own food using sunlight is called:
C. Photosynthesis — Photosynthesis uses sunlight, carbon dioxide and water in the chlorophyll of leaves to make glucose and release oxygen. Respiration is the reverse process that releases energy.
Q5. The image formed on the retina of a normal human eye is:
A. Real and inverted — The convex lens of the eye forms a real, inverted, diminished image on the retina. The brain interprets it as upright.
Q6. During respiration, glucose is broken down mainly to release:
B. Energy — Respiration breaks down glucose (usually with oxygen) to release energy stored as ATP, along with carbon dioxide and water.
Q7. A chemical reaction in which a single reactant breaks down into two or more simpler products is best classified as a:
B. Decomposition reaction — In a decomposition reaction one compound splits into simpler substances, often on heating, exposure to light, or passing electricity.
Q8. Which of the following solutions has a pH value greater than 7?
C. Milk of magnesia — Milk of magnesia is a suspension of magnesium hydroxide, a base, so its pH is above 7; the other three are acidic (pH below 7).
Q9. Which metal, when added to an aqueous solution of copper sulphate, will displace copper from it?
D. Iron — Iron lies above copper in the reactivity series, so it is more reactive and displaces copper; silver, gold and mercury are less reactive than copper.
Q10. The functional group present in ethanoic acid (acetic acid) is the:
C. Carboxylic acid group (-COOH) — Ethanoic acid, CH3COOH, contains the -COOH carboxylic acid functional group, which gives it its acidic character.
Q11. Which of the following is an endothermic reaction?
D. Thermal decomposition of calcium carbonate — Heating calcium carbonate to form calcium oxide and carbon dioxide absorbs heat, making it endothermic; combustion, respiration and neutralisation all release heat.
Q12. In the human respiratory system, the exchange of gases between the blood and the air takes place in the:
A. Alveoli — The alveoli are thin-walled, balloon-like air sacs with a rich blood supply, providing a large surface for oxygen and carbon dioxide exchange.
Q13. Which endocrine gland secretes the hormone insulin?
B. Pancreas — Insulin is produced by the pancreas and lowers blood glucose; its deficiency causes diabetes.
Q14. Reflex actions in the human body, such as pulling the hand away from a hot object, are controlled mainly by the:
C. Spinal cord — Reflex arcs are completed through the spinal cord, allowing a rapid response without waiting for the brain to process the signal.
Q15. Which of the following organisms reproduces asexually by budding?
C. Hydra — Hydra reproduces by budding, where a small outgrowth develops into a new individual; Amoeba uses binary fission, Plasmodium multiple fission, and Planaria regeneration.
Q16. When two pea plants heterozygous for height (Tt) are crossed, the ratio of tall to dwarf plants obtained in the offspring is:
A. 3 : 1 — A Tt x Tt cross gives genotypes 1 TT : 2 Tt : 1 tt, but since T is dominant the visible (phenotypic) ratio of tall to dwarf is 3 : 1.
Q17. The forelimb of a human and the wing of a bird have a similar basic structure but perform different functions. Such organs are called:
B. Homologous organs — Homologous organs share the same fundamental structure and origin but may be adapted for different functions, indicating common ancestry.
Q18. A person who cannot see distant objects clearly suffers from myopia. This defect is corrected by using spectacles with a:
A. Concave lens — Myopia is corrected with a concave (diverging) lens of suitable power, which moves the image back onto the retina.
Q19. The power of a convex lens whose focal length is 50 cm is:
D. +2 D — Power = 1/f (in metres) = 1/0.5 = +2 dioptres for a converging lens.
Q20. Two resistors of 2 ohm and 3 ohm are connected in series. The equivalent resistance of the combination is:
B. 5 ohm — In series, resistances add up: 2 + 3 = 5 ohm. (1.2 ohm would be the parallel combination.)
Q21. The magnetic field lines inside a long current-carrying solenoid are:
D. Parallel straight lines — Inside a solenoid the magnetic field is nearly uniform, shown by parallel straight field lines, similar to the field of a bar magnet outside it.
Q22. In a food chain, the approximate percentage of energy transferred from one trophic level to the next is:
C. 10% — According to the ten percent law, only about 10% of the energy at one trophic level is passed on to the next; the rest is lost mainly as heat.
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