Questions on Molar Mass
Multiple-Choice Questions: Molar Mass
1. What is the molar mass of water (H₂O)?
A) 10.0 g/mol
B) 16.0 g/mol
C) 18.0 g/mol
D) 20.0 g/mol
E) 12.0 g/mol
2. Which compound has a molar mass closest to 44.0 g/mol?
A) CH₄
B) CO₂
C) H₂O
D) NH₃
E) O₂
3. What is the molar mass of NaCl? (Na = 23, Cl = 35.5)
A) 58.5 g/mol
B) 60.0 g/mol
C) 55.0 g/mol
D) 50.5 g/mol
E) 57.0 g/mol
4. What is the molar mass of glucose (C₆H₁₂O₆)?
A) 160 g/mol
B) 180 g/mol
C) 200 g/mol
D) 210 g/mol
E) 120 g/mol
5. Which of the following has the lowest molar mass?
A) CO₂
B) CH₄
C) NH₃
D) H₂O
E) H₂
6. What is the molar mass of sulfuric acid (H₂SO₄)?
A) 94 g/mol
B) 96 g/mol
C) 98 g/mol
D) 100 g/mol
E) 102 g/mol
7. What is the molar mass of calcium carbonate (CaCO₃)? (Ca = 40, C = 12, O = 16)
A) 100 g/mol
B) 92 g/mol
C) 88 g/mol
D) 106 g/mol
E) 98 g/mol
8. Which compound has a molar mass of approximately 34 g/mol?
A) H₂O₂
B) NH₃
C) H₂S
D) CH₄
E) O₂
9. What is the molar mass of methane (CH₄)?
A) 12 g/mol
B) 14 g/mol
C) 16 g/mol
D) 18 g/mol
E) 20 g/mol
10. What is the molar mass of aluminum sulfate, Al₂(SO₄)₃? (Al = 27, S = 32, O = 16)
A) 294 g/mol
B) 314 g/mol
C) 342 g/mol
D) 366 g/mol
E) 278 g/mol
11. What is the molar mass of ethanol (C₂H₅OH)?
A) 42 g/mol
B) 46 g/mol
C) 50 g/mol
D) 52 g/mol
E) 48 g/mol
12. Which compound has a molar mass of about 28 g/mol?
A) CO
B) N₂
C) NO
D) O₂
E) All of the above
13. What is the molar mass of nitrogen gas (N₂)?
A) 14.0 g/mol
B) 15.0 g/mol
C) 16.0 g/mol
D) 28.0 g/mol
E) 30.0 g/mol
14. What is the molar mass of potassium hydroxide (KOH)? (K = 39, O = 16, H = 1)
A) 54 g/mol
B) 56 g/mol
C) 57 g/mol
D) 59 g/mol
E) 60 g/mol
15. What is the molar mass of magnesium nitrate, Mg(NO₃)₂? (Mg = 24, N = 14, O = 16)
A) 112 g/mol
B) 128 g/mol
C) 148 g/mol
D) 96 g/mol
E) 116 g/mol
16. What is the molar mass of acetic acid (CH₃COOH)?
A) 60 g/mol
B) 62 g/mol
C) 64 g/mol
D) 58 g/mol
E) 66 g/mol
17. Which of the following compounds has the highest molar mass?
A) H₂SO₄
B) HNO₃
C) H₃PO₄
D) HCl
E) HF
18. What is the molar mass of phosphoric acid (H₃PO₄)? (H = 1, P = 31, O = 16)
A) 96 g/mol
B) 98 g/mol
C) 100 g/mol
D) 102 g/mol
E) 104 g/mol
19. What is the molar mass of barium chloride (BaCl₂)? (Ba = 137, Cl = 35.5)
A) 202 g/mol
B) 208 g/mol
C) 210 g/mol
D) 207 g/mol
E) 215 g/mol
20. What is the molar mass of sodium carbonate (Na₂CO₃)? (Na = 23, C = 12, O = 16)
A) 100 g/mol
B) 105 g/mol
C) 110 g/mol
D) 98 g/mol
E) 108 g/mol
- Questions on Conversions Between Moles and Atoms
- Questions on Conversions Between Moles and Mass
- Questions on Conversions Between Mass and Number of Particles
Answers with Explanations
1. C) 18.0 g/mol → H₂O = (2×1) + 16 = 18
2. B) CO₂ → C = 12, O₂ = 32 → total = 44
3. A) 58.5 g/mol → 23 (Na) + 35.5 (Cl) = 58.5
4. B) 180 g/mol → C₆H₁₂O₆ = (6×12) + (12×1) + (6×16) = 180
5. E) H₂ → 2×1 = 2 g/mol
6. C) 98 g/mol → H₂SO₄ = (2×1) + 32 + (4×16) = 98
7. A) 100 g/mol → 40 (Ca) + 12 (C) + 48 (O) = 100
8. A) H₂O₂ → (2×1) + (2×16) = 34
9. C) 16 g/mol → C = 12, H₄ = 4 → total = 16
10. C) 342 g/mol → (2×27) + (3×(32 + (4×16))) = 342
11. B) 46 g/mol → C₂H₆O = (2×12) + (6×1) + 16 = 46
12. E) All of the above → CO (12+16=28), N₂ (14×2=28), NO (14+16=30 close)
13. D) 28.0 g/mol → N = 14 × 2 = 28
14. B) 56 g/mol → K = 39, O = 16, H = 1 → total = 56
15. A) 148 g/mol → 24 + 2×(14 + (3×16)) = 148
16. A) 60 g/mol → CH₃COOH = (2×12) + (4×1) + (2×16) = 60
17. A) H₂SO₄ → Highest mass = 98 g/mol
18. A) 96 g/mol → H₃PO₄ = (3×1) + 31 + (4×16) = 96
19. A) 202 g/mol → 137 + (2×35.5) = 202
20. A) 106 g/mol → (2×23) + 12 + (3×16) = 106
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