“Stoichiometry” MCQ with Answer Explanation.

51. In the reaction 3H₂ + N₂ → 2NH₃, how many moles of NH₃ are produced from 3 moles of H₂?

A) 1.5 moles
B) 2 moles
C) 3 moles
D) 4 moles

Answer: A) 3 moles

Explanation: The reaction shows that 3 moles of H₂ produce 2 moles of NH₃, so 3 moles of H₂ will yield 2 moles of NH₃.

52. How many grams of KCl are in 3 moles? (Molar mass of KCl = 74.5 g/mol)

A) 149 g
B) 224 g
C) 300 g
D) 448.5 g

Answer: A) 224 g

Explanation: Mass = moles × molar mass = 3 moles × 74.5 g/mol = 223.5 g.

53. In the reaction 2Na + 2H₂O → 2NaOH + H₂, how many moles of NaOH are produced from 5 moles of Na?

A) 2.5 moles
B) 5 moles
C) 10 moles
D) 15 moles

Answer: B) 5 moles

Explanation: The balanced equation indicates that 2 moles of Na produce 2 moles of NaOH, so 5 moles of Na will produce 5 moles of NaOH.

54. If 1 mole of glucose (C₆H₁₂O₆) is fermented, how many moles of carbon dioxide are produced? (C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂)

A) 1 mole
B) 2 moles
C) 3 moles
D) 4 moles

Answer: B) 2 moles

Explanation: The fermentation process shows that 1 mole of glucose produces 2 moles of CO₂.

55. How many moles of CO are produced from the complete combustion of 2 moles of methanol (CH₃OH)? (2CH₃OH + 3O₂ → 2CO₂ + 4H₂O)

A) 2 moles
B) 4 moles
C) 6 moles
D) 8 moles

Answer: A) 2 moles

Explanation: The reaction shows that 2 moles of methanol produce 2 moles of CO.

56. What is the mass of 0.25 moles of CaCO₃? (Molar mass of CaCO₃ = 100 g/mol)

A) 25 g
B) 50 g
C) 75 g
D) 100 g

Answer: B) 25 g

Explanation: Mass = moles × molar mass = 0.25 moles × 100 g/mol = 25 g.

57. In the reaction 2K + Cl₂ → 2KCl, how many moles of Cl₂ are needed to react with 4 moles of K?

A) 1 mole
B) 2 moles
C) 3 moles
D) 4 moles

Answer: B) 2 moles

Explanation: The balanced equation shows that 2 moles of K react with 1 mole of Cl₂, so 4 moles of K will require 2 moles of Cl₂.

58. How many grams of NH₃ can be produced from 3 moles of N₂? (N₂ + 3H₂ → 2NH₃; Molar mass of NH₃ = 17 g/mol)

A) 51 g
B) 102 g
C) 153 g
D) 204 g

Answer: B) 102 g

Explanation: 3 moles of N₂ produce 6 moles of NH₃, so mass = 6 moles × 17 g/mol = 102 g.

59. How many liters of CO₂ are produced from 2 moles of C₆H₁₂O₆? (C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O; at STP 1 mole = 22.4 L)

A) 44.8 L
B) 134.4 L
C) 268.8 L
D) 400 L

Answer: C) 268.8 L

Explanation: 2 moles of glucose produce 12 moles of CO₂, so volume = 12 × 22.4 L = 268.8 L.

60. What is the molar mass of aluminum sulfate (Al₂(SO₄)₃)?

A) 150 g/mol
B) 200 g/mol
C) 250 g/mol
D) 300 g/mol

Answer: C) 342 g/mol

Explanation: Molar mass = (2×27) + (3×32) + (12×16) = 54 + 96 + 192 = 342 g/mol