“Mole Concept” MCQ with Answer Explanation : NEET 2025.

51. How many grams are in 0.2 moles of KCl (Molar mass = 74.5 g/mol)?
    a) 14.9 g
    b) 15 g
    c) 20 g
    d) 25 g

Answer: a) 14.9 g

Explanation: 0.2 moles × 74.5 g/mol = 14.9 g.

52. The number of moles in 64 g of O₂ is:
    a) 1 mole
    b) 2 moles
    c) 3 moles
    d) 4 moles

Answer: b) 2 moles

Explanation: 64 g ÷ 32 g/mol = 2 moles.

53. In the reaction 4Fe + 3O₂ → 2Fe₂O₃, how many moles of Fe are required to react with 1 mole of O₂?
    a) 4/3 moles
    b) 2 moles
    c) 1.5 moles
    d) 3 moles

Answer: a) 4/3 moles

Explanation: The mole ratio indicates that 4 moles of Fe react with 3 moles of O₂, so 1 mole of O₂ requires 4/3 moles of Fe.

54. What is the molar mass of ammonium nitrate (NH₄NO₃)?
    a) 80 g/mol
    b) 90 g/mol
    c) 100 g/mol
    d) 150 g/mol

Answer: b) 90 g/mol

Explanation: Molar mass is calculated as (14 + 4) + (14 + 3 × 16) = 90 g/mol.

55. How many molecules are in 4 moles of glucose (C₆H₁₂O₆)?
    a) 2.41 × 10²³
    b) 2.41 × 10²⁴
    c) 1.81 × 10²⁴
    d) 3.01 × 10²²

Answer: b) 2.41 × 10²⁴

Explanation: 4 moles × 6.022 × 10²³ molecules/mole = 2.41 × 10²⁴ molecules.

56. The molar mass of phosphoric acid (H₃PO₄) is:
    a) 95 g/mol
    b) 98 g/mol
    c) 100 g/mol
    d) 105 g/mol

Answer: b) 98 g/mol

Explanation: Molar mass is calculated as (3 × 1) + (31) + (4 × 16) = 98 g/mol.

57. In a chemical reaction, if you have 1 mole of A and it reacts with 3 moles of B, what is the total number of moles of products formed if 1 mole of A is completely consumed?
    a) 1 mole
    b) 2 moles
    c) 4 moles
    d) 3 moles

Answer: c) 4 moles

Explanation: If 1 mole of A and 3 moles of B react, the total moles of products will be the sum of moles of A and B consumed.

58. What is the volume occupied by 3 moles of an ideal gas at STP?
    a) 33.6 L
    b) 67.2 L
    c) 22.4 L
    d) 60 L

Answer: b) 67.2 L

Explanation: 3 moles × 22.4 L/mole = 67.2 L.

59. The mass of 2.5 moles of CaCO₃ (Molar mass = 100 g/mol) is:
    a) 250 g
    b) 200 g
    c) 150 g
    d) 125 g

Answer: a) 250 g

Explanation: 2.5 moles × 100 g/mol = 250 g.

60. How many moles of K are in 100 g of KCl (Molar mass = 74.5 g/mol)?
    a) 1.35 moles
    b) 2.35 moles
    c) 1.5 moles
    d) 0.5 moles

Answer: a) 1.35 moles

Explanation: 100 g ÷ 74.5 g/mol = 1.35 moles of KCl, which contains 1.35 moles of K.