Central Board of Secondary Education (CBSE - India) Class 10 Science MCQs: Chemical Reactions and Equations, Acids, Bases and Salts, Periodic Classification of Elements +4 more

Instructions. Answer all questions. Fill exactly one bubble per question on the OMR sheet.

1. Chemical Reactions and Equations

   1.

   Which of the following processes involves a chemical reaction?

   1. (A)

      Boiling of water

   2. (B)

      Dissolving salt in water

   3. (C)

      Melting of ice

   4. (D)

      Burning of magnesium ribbon

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   Answer: (D)

   Burning of magnesium ribbon

   Chemical Reactions and Equations · Easy

2. 2.

   What type of reaction is represented by the equation: $CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq)$?

   1. (A)

      Combination reaction

   2. (B)

      Displacement reaction

   3. (C)

      Decomposition reaction

   4. (D)

      Double displacement reaction

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   Answer: (A)

   Combination reaction

   Chemical Reactions and Equations · Medium

3. 3.

   When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is formed and sulphuric acid is produced. Which type of reaction is this?

   1. (A)

      Double displacement reaction

   2. (B)

      Displacement reaction

   3. (C)

      Decomposition reaction

   4. (D)

      Combination reaction

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   Answer: (A)

   Double displacement reaction

   Chemical Reactions and Equations · Medium

4. 4.

   A student added dilute hydrochloric acid to a test tube containing zinc granules. Which of the following observations is incorrect?

   1. (A)

      The test tube becomes hot.

   2. (B)

      Zinc granules turn black.

   3. (C)

      Zinc chloride solution is formed.

   4. (D)

      A gas is evolved.

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   Answer: (B)

   Zinc granules turn black.

   Chemical Reactions and Equations · Hard

5. 5.

   Which of the following statements about the reaction $2Na(s) + O_2(g) \rightarrow 2Na_2O(s)$ is incorrect?

   1. (A)

      Sodium is acting as a reducing agent.

   2. (B)

      Oxygen is acting as an oxidizing agent.

   3. (C)

      This is a redox reaction.

   4. (D)

      Sodium is getting oxidized.

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   Answer: (A)

   Sodium is acting as a reducing agent.

   Chemical Reactions and Equations · Hard

6. Acids, Bases and Salts

   6.

   Which of the following statements is true about the $\text{pH}$ of a solution?

   1. (A)

      A $\text{pH}$ above 7 indicates an acidic solution.

   2. (B)

      A $\text{pH}$ of 7 indicates a strongly acidic solution.

   3. (C)

      A $\text{pH}$ below 7 indicates a basic solution.

   4. (D)

      A $\text{pH}$ of 7 indicates a neutral solution.

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   Answer: (D)

   A $\text{pH}$ of 7 indicates a neutral solution.

   Acids, Bases and Salts · Easy

7. 7.

   When an acid reacts with a base, the products are usually:

   1. (A)

      Base and water

   2. (B)

      Salt and water

   3. (C)

      Salt and hydrogen gas

   4. (D)

      Acid and salt

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   Answer: (B)

   Salt and water

   Acids, Bases and Salts · Easy

8. 8.

   A student adds a few drops of universal indicator to an unknown solution. The solution turns blue. What is the nature of the unknown solution?

   1. (A)

      Weakly acidic

   2. (B)

      Neutral

   3. (C)

      Basic

   4. (D)

      Strongly acidic

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   Answer: (C)

   Basic

   Acids, Bases and Salts · Medium

9. 9.

   Which gas is typically produced when a dilute acid reacts with a metal like zinc?

   1. (A)

      Oxygen

   2. (B)

      Carbon dioxide

   3. (C)

      Sulphur dioxide

   4. (D)

      Hydrogen

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   Answer: (D)

   Hydrogen

   Acids, Bases and Salts · Easy

10. 10.

    Sodium carbonate reacts with hydrochloric acid to produce sodium chloride, water, and another product. What is this third product?

    1. (A)

       Hydrogen gas

    2. (B)

       Sulphur dioxide gas

    3. (C)

       Carbon dioxide gas

    4. (D)

       Oxygen gas

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    Answer: (C)

    Carbon dioxide gas

    Acids, Bases and Salts · Medium

11. Periodic Classification of Elements

    11.

    Which scientist proposed the Law of Octaves, arranging elements in groups of eight based on similar properties?

    1. (A)

       J.W. Dobereiner

    2. (B)

       Lothar Meyer

    3. (C)

       Dmitri Mendeleev

    4. (D)

       John Newlands

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    Answer: (D)

    John Newlands

    Periodic Classification of Elements · Easy

12. 12.

    What is the main reason for the anomalous behavior of the first element in each group (e.g., lithium in Group 1, boron in Group 13) in the modern periodic table?

    1. (A)

       Its large atomic size and low ionization enthalpy

    2. (B)

       Its small atomic size and low electron gain enthalpy

    3. (C)

       Its small atomic size and high electronegativity

    4. (D)

       Its large atomic size and high electronegativity

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    Answer: (C)

    Its small atomic size and high electronegativity

    Periodic Classification of Elements · Medium

13. 13.

    An element has an atomic number of 17. To which group and period of the modern periodic table does this element belong?

    1. (A)

       Group 7, Period 2

    2. (B)

       Group 17, Period 3

    3. (C)

       Group 7, Period 3

    4. (D)

       Group 17, Period 2

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    Answer: (B)

    Group 17, Period 3

    Periodic Classification of Elements · Medium

14. 14.

    Which of the following statements is true regarding the trend of metallic character across a period in the modern periodic table?

    1. (A)

       Metallic character remains constant across a period.

    2. (B)

       Metallic character first increases then decreases.

    3. (C)

       Metallic character increases from left to right.

    4. (D)

       Metallic character decreases from left to right.

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    Answer: (D)

    Metallic character decreases from left to right.

    Periodic Classification of Elements · Easy

15. 15.

    Element X forms a chloride with the formula $XCl_2$. To which group of the modern periodic table is element X most likely to belong?

    1. (A)

       Group 1

    2. (B)

       Group 2

    3. (C)

       Group 14

    4. (D)

       Group 13

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    Answer: (B)

    Group 2

    Periodic Classification of Elements · Hard

16. Life Processes

    16.

    Which component of blood is primarily responsible for transporting oxygen to different parts of the body?

    1. (A)

       Plasma

    2. (B)

       Platelets

    3. (C)

       Red blood cells

    4. (D)

       White blood cells

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    Answer: (C)

    Red blood cells

    Life Processes · Easy

17. 17.

    During photosynthesis, what is the primary role of chlorophyll?

    1. (A)

       To break down glucose into energy

    2. (B)

       To capture light energy from the sun

    3. (C)

       To release oxygen into the atmosphere

    4. (D)

       To absorb water from the soil

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    Answer: (B)

    To capture light energy from the sun

    Life Processes · Medium

18. 18.

    Which of the following describes the correct path of urine flow in the human excretory system?

    1. (A)

       Kidneys → Ureters → Urinary bladder → Urethra

    2. (B)

       Urinary bladder → Kidneys → Ureters → Urethra

    3. (C)

       Kidneys → Urinary bladder → Ureters → Urethra

    4. (D)

       Kidneys → Urethra → Ureters → Urinary bladder

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    Answer: (A)

    Kidneys → Ureters → Urinary bladder → Urethra

    Life Processes · Medium

19. 19.

    What is the function of villi in the small intestine?

    1. (A)

       To absorb water from undigested food

    2. (B)

       To store bile for fat digestion

    3. (C)

       To increase the surface area for nutrient absorption

    4. (D)

       To produce digestive enzymes

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    Answer: (C)

    To increase the surface area for nutrient absorption

    Life Processes · Easy

20. 20.

    A student observed that a plant kept in a dark room for several days started to turn yellow. Which essential life process is most affected by the absence of light for this observation?

    1. (A)

       Photosynthesis

    2. (B)

       Respiration

    3. (C)

       Transpiration

    4. (D)

       Absorption

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    Answer: (A)

    Photosynthesis

    Life Processes · Hard

21. Carbon and its Compounds

    21.

    Which of the following represents the correct order of increasing valency for carbon, nitrogen, and oxygen?

    1. (A)

       Nitrogen < Oxygen < Carbon

    2. (B)

       Oxygen < Nitrogen < Carbon

    3. (C)

       Carbon < Nitrogen < Oxygen

    4. (D)

       Oxygen < Carbon < Nitrogen

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    Answer: (B)

    Oxygen < Nitrogen < Carbon

    Carbon and its Compounds · Medium

22. 22.

    What is the general formula for alkenes?

    1. (A)

       $C_nH_{2n}$

    2. (B)

       $C_nH_{2n+1}$

    3. (C)

       $C_nH_{2n-2}$

    4. (D)

       $C_nH_{2n+2}$

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    Answer: (A)

    $C_nH_{2n}$

    Carbon and its Compounds · Easy

23. 23.

    Ethanoic acid reacts with ethanol in the presence of concentrated sulfuric acid. What is the main product of this reaction?

    1. (A)

       Ethene

    2. (B)

       Diethyl ether

    3. (C)

       Ethanal

    4. (D)

       Ethyl ethanoate

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    Answer: (D)

    Ethyl ethanoate

    Carbon and its Compounds · Medium

24. 24.

    Which of the following properties is generally true for ionic compounds but not for covalent compounds?

    1. (A)

       They exist as discrete molecules.

    2. (B)

       They have low melting and boiling points.

    3. (C)

       They conduct electricity in molten state or aqueous solution.

    4. (D)

       They are soluble in non-polar solvents.

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    Answer: (C)

    They conduct electricity in molten state or aqueous solution.

    Carbon and its Compounds · Hard

25. 25.

    When methane undergoes incomplete combustion, what are the primary products formed?

    1. (A)

       Carbon monoxide and water

    2. (B)

       Carbon and hydrogen

    3. (C)

       Carbon dioxide and hydrogen

    4. (D)

       Carbon dioxide and water

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    Answer: (A)

    Carbon monoxide and water

    Carbon and its Compounds · Easy

26. How do Organisms Reproduce?

    26.

    Which method of asexual reproduction involves the development of an organism from an unfertilised egg?

    1. (A)

       Spore formation

    2. (B)

       Parthenogenesis

    3. (C)

       Regeneration

    4. (D)

       Budding

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    Answer: (B)

    Parthenogenesis

    How do Organisms Reproduce? · Medium

27. 27.

    In human females, where does the fertilisation of an egg cell by a sperm typically occur?

    1. (A)

       Ovary

    2. (B)

       Fallopian tube

    3. (C)

       Uterus

    4. (D)

       Vagina

    Show answerHide answer

    Answer: (B)

    Fallopian tube

    How do Organisms Reproduce? · Easy

28. 28.

    Which of the following is a sexually transmitted disease caused by a bacterium?

    1. (A)

       HIV/AIDS

    2. (B)

       Warts

    3. (C)

       Gonorrhoea

    4. (D)

       Hepatitis B

    Show answerHide answer

    Answer: (C)

    Gonorrhoea

    How do Organisms Reproduce? · Medium

29. 29.

    What is the primary function of the placenta in human pregnancy?

    1. (A)

       To protect the fetus from physical shocks

    2. (B)

       To produce hormones for fetal development

    3. (C)

       To facilitate exchange of nutrients and waste between mother and fetus

    4. (D)

       To store genetic information for the fetus

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    Answer: (C)

    To facilitate exchange of nutrients and waste between mother and fetus

    How do Organisms Reproduce? · Hard

30. 30.

    Which part of a flower develops into a fruit after fertilisation?

    1. (A)

       Stamen

    2. (B)

       Sepal

    3. (C)

       Ovary

    4. (D)

       Petal

    Show answerHide answer

    Answer: (C)

    Ovary

    How do Organisms Reproduce? · Easy

31. Control and Coordination

    31.

    Which part of the brain is responsible for maintaining posture and balance of the body?

    1. (A)

       Medulla

    2. (B)

       Hypothalamus

    3. (C)

       Cerebellum

    4. (D)

       Cerebrum

    Show answerHide answer

    Answer: (C)

    Cerebellum

    Control and Coordination · Easy

32. 32.

    What is the primary function of the dendrites in a neuron?

    1. (A)

       To receive signals from other neurons

    2. (B)

       To transmit signals away from the cell body

    3. (C)

       To produce neurotransmitters

    4. (D)

       To insulate the axon

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    Answer: (A)

    To receive signals from other neurons

    Control and Coordination · Medium

33. 33.

    Which of the following plant hormones is primarily responsible for the growth of the stem and leaves?

    1. (A)

       Auxin

    2. (B)

       Cytokinin

    3. (C)

       Ethylene

    4. (D)

       Abscisic acid

    Show answerHide answer

    Answer: (A)

    Auxin

    Control and Coordination · Easy

34. 34.

    Damage to which part of the brain would most likely affect a person's ability to regulate heart rate and breathing?

    1. (A)

       Medulla oblongata

    2. (B)

       Thalamus

    3. (C)

       Cerebral cortex

    4. (D)

       Hippocampus

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    Answer: (A)

    Medulla oblongata

    Control and Coordination · Medium

35. 35.

    A person experiences sudden withdrawal of their hand upon touching a hot object. This reflex action is coordinated by which part of the nervous system?

    1. (A)

       Cerebrum

    2. (B)

       Hypothalamus

    3. (C)

       Spinal cord

    4. (D)

       Cerebellum

    Show answerHide answer

    Answer: (C)

    Spinal cord

    Control and Coordination · Hard

— End of the paper · updated 11 November 2026 —