Chemical Reactions and Equations Part 2: MCQs (Q26–Q50)

⚗️ Chemical Reactions and Equations – Class 10 Science MCQs

Part 2: Types of Chemical Reactions (Q26–Q50)

Q26. The reaction: 2Mg + O₂ → 2MgO is an example of:

A. Combination reaction
B. Decomposition reaction
C. Displacement reaction
D. Neutralization reaction

✅ Correct Answer: A. Combination reaction

Explanation: Two reactants combine → single product.

Q27. Which reaction is an example of decomposition?

A. CaCO₃ → CaO + CO₂
B. 2Mg + O₂ → 2MgO
C. NaOH + HCl → NaCl + H₂O
D. Fe + CuSO₄ → FeSO₄ + Cu

✅ Correct Answer: A. CaCO₃ → CaO + CO₂

Explanation: Single compound breaks → two simpler products.

Q28. Thermal decomposition of silver nitrate gives:

A. Ag + O₂ + NO₂
B. Ag₂O + NO₂
C. AgNO₂ + O₂
D. Ag₂O + NO

✅ Correct Answer: A. Ag + O₂ + NO₂

Q29. Which of the following is NOT a decomposition reaction?

A. 2KClO₃ → 2KCl + 3O₂
B. CaCO₃ → CaO + CO₂
C. 2Mg + O₂ → 2MgO
D. Pb(NO₃)₂ → PbO + NO₂ + O₂

✅ Correct Answer: C. 2Mg + O₂ → 2MgO

Explanation: This is combination, not decomposition.

Q30. The electrolysis of water produces:

A. H₂ + O₂
B. H₂O₂
C. O₃
D. H₂ only

✅ Correct Answer: A. H₂ + O₂

Q31. The reaction: Fe + CuSO₄ → FeSO₄ + Cu is an example of:

A. Double displacement
B. Combination
C. Displacement
D. Decomposition

✅ Correct Answer: C. Displacement

Q32. Which of these metals can displace hydrogen from dilute acids?

A. Copper
B. Silver
C. Zinc
D. Gold

✅ Correct Answer: C. Zinc

Explanation: Only metals above hydrogen in reactivity series (e.g., Zn, Mg) can displace H₂ from acids.

Q33. The reaction: AgNO₃ + NaCl → AgCl + NaNO₃ is:

A. Displacement
B. Double displacement
C. Combination
D. Decomposition

✅ Correct Answer: B. Double displacement

Q34. In double displacement reaction, two compounds:

A. Exchange ions
B. Combine to form one product
C. Decompose into simple products
D. Exchange protons only

✅ Correct Answer: A. Exchange ions

Q35. The reaction between an acid and a base is called:

A. Neutralization reaction
B. Combination reaction
C. Decomposition reaction
D. Displacement reaction

✅ Correct Answer: A. Neutralization reaction

Q36. Which type of reaction is: BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl?

A. Displacement
B. Double displacement (precipitation)
C. Decomposition
D. Combination

✅ Correct Answer: B. Double displacement (precipitation)

Q37. Which is NOT a redox reaction?

A. Zn + CuSO₄ → ZnSO₄ + Cu
B. 2Mg + O₂ → 2MgO
C. NaOH + HCl → NaCl + H₂O
D. 2KClO₃ → 2KCl + 3O₂

✅ Correct Answer: C. NaOH + HCl → NaCl + H₂O

Explanation: Neutralization, no oxidation/reduction.

Q38. In a redox reaction:

A. Both oxidation and reduction occur simultaneously
B. Only oxidation occurs
C. Only reduction occurs
D. Neither oxidation nor reduction occurs

✅ Correct Answer: A. Both oxidation and reduction occur simultaneously

Q39. Oxidation involves:

A. Loss of electrons
B. Gain of electrons
C. Loss of protons
D. No electron transfer

✅ Correct Answer: A. Loss of electrons

Q40. Reduction involves:

A. Loss of electrons
B. Gain of electrons
C. Loss of protons
D. Breaking of bonds only

✅ Correct Answer: B. Gain of electrons

Q41. Which of the following is reduced in: Zn + CuSO₄ → ZnSO₄ + Cu?

A. Zn
B. Cu²⁺
C. SO₄²⁻
D. O₂

✅ Correct Answer: B. Cu²⁺

Q42. Which of the following is oxidized in: Zn + CuSO₄ → ZnSO₄ + Cu?

A. Zn
B. Cu²⁺
C. SO₄²⁻
D. O₂

✅ Correct Answer: A. Zn

Q43. In 2Mg + O₂ → 2MgO, magnesium is:

A. Oxidized
B. Reduced
C. Both oxidized and reduced
D. Neither

✅ Correct Answer: A. Oxidized

Q44. In the same reaction (2Mg + O₂ → 2MgO), oxygen is:

A. Oxidized
B. Reduced
C. Both oxidized and reduced
D. Neither

✅ Correct Answer: B. Reduced

Q45. Which reaction is used in the extraction of metals from oxides?

A. Combination
B. Reduction
C. Displacement
D. Decomposition

✅ Correct Answer: B. Reduction

Q46. Which of these is an example of both combination and redox reaction?

A. CaO + H₂O → Ca(OH)₂
B. 2Mg + O₂ → 2MgO
C. NaOH + HCl → NaCl + H₂O
D. Zn + CuSO₄ → ZnSO₄ + Cu

✅ Correct Answer: B. 2Mg + O₂ → 2MgO

Q47. Which of the following is a precipitation reaction?

A. AgNO₃ + NaCl → AgCl + NaNO₃
B. CaO + H₂O → Ca(OH)₂
C. Zn + CuSO₄ → ZnSO₄ + Cu
D. CaCO₃ → CaO + CO₂

✅ Correct Answer: A. AgNO₃ + NaCl → AgCl + NaNO₃

Q48. When HCl reacts with NaOH, the type of reaction is:

A. Combination
B. Neutralization (double displacement)
C. Decomposition
D. Redox

✅ Correct Answer: B. Neutralization (double displacement)

Q49. Which type of chemical reaction is respiration?

A. Combination and exothermic
B. Decomposition and endothermic
C. Neutralization
D. Displacement

✅ Correct Answer: A. Combination and exothermic

Explanation: Glucose combines with O₂ → CO₂ + H₂O + energy.

Q50. The reaction: Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl is an example of:

A. Combination
B. Decomposition
C. Displacement
D. Double displacement

✅ Correct Answer: D. Double displacement

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