Questions on Conversions Between Mass and Number of Particles
Multiple-Choice Questions: Conversions Between Mass and Number of Particles
1. How many molecules are in 18.0 g of water (H₂O)?
A) 1.00 × 10²²
B) 6.02 × 10²³
C) 3.01 × 10²³
D) 1.20 × 10²⁴
E) 9.03 × 10²³
2. How many atoms are in 12.0 g of carbon? (C = 12.0 g/mol)
A) 6.02 × 10²³
B) 3.01 × 10²³
C) 1.00 × 10²³
D) 2.00 × 10²³
E) 1.20 × 10²⁴
3. What is the number of formula units in 58.5 g of NaCl? (NaCl = 58.5 g/mol)
A) 6.02 × 10²³
B) 1.20 × 10²⁴
C) 3.01 × 10²³
D) 5.02 × 10²²
E) 2.00 × 10²³
4. How many oxygen atoms are in 36.0 g of water? (H₂O = 18.0 g/mol)
A) 6.02 × 10²³
B) 1.20 × 10²⁴
C) 2.41 × 10²⁴
D) 3.01 × 10²³
E) 2.00 × 10²³
5. How many hydrogen atoms are in 18.0 g of water?
A) 6.02 × 10²³
B) 1.20 × 10²⁴
C) 2.41 × 10²⁴
D) 1.20 × 10²³
E) 4.00 × 10²³
6. How many molecules are in 90.0 g of glucose (C₆H₁₂O₆, M = 180 g/mol)?
A) 3.01 × 10²³
B) 6.02 × 10²²
C) 1.20 × 10²⁴
D) 9.03 × 10²³
E) 2.00 × 10²³
7. How many atoms are in 4.00 g of He? (He = 4.00 g/mol)
A) 2.00 × 10²³
B) 6.02 × 10²³
C) 4.00 × 10²³
D) 1.50 × 10²⁴
E) 8.00 × 10²³
8. How many total atoms are in 1 molecule of H₂SO₄?
A) 4
B) 6
C) 7
D) 5
E) 2
9. How many total atoms are in 98.0 g of H₂SO₄? (M = 98.0 g/mol)
A) 6.02 × 10²³
B) 3.01 × 10²⁴
C) 4.21 × 10²⁴
D) 7.00 × 10²³
E) 8.43 × 10²⁴
10. How many formula units are in 100.0 g of CaCO₃? (M = 100.0 g/mol)
A) 6.02 × 10²³
B) 1.20 × 10²⁴
C) 3.01 × 10²³
D) 4.00 × 10²³
E) 8.00 × 10²²
11. What is the number of atoms in 2.0 mol of copper? (Cu = 63.5 g/mol)
A) 6.02 × 10²³
B) 1.20 × 10²⁴
C) 3.00 × 10²³
D) 2.00 × 10²³
E) 9.03 × 10²³
12. How many particles are in 0.50 mol of any substance?
A) 3.01 × 10²³
B) 1.00 × 10²³
C) 6.02 × 10²³
D) 1.20 × 10²⁴
E) 2.50 × 10²³
13. How many oxygen atoms are in 1 mol of CO₂?
A) 1.00 × 10²³
B) 6.02 × 10²³
C) 1.20 × 10²⁴
D) 3.01 × 10²³
E) 2.00 × 10²⁴
14. How many particles are in 4.00 g of H₂? (H₂ = 2.00 g/mol)
A) 6.02 × 10²³
B) 1.20 × 10²⁴
C) 3.01 × 10²³
D) 9.03 × 10²³
E) 2.00 × 10²³
15. What is the number of water molecules in 9.0 g of water?
A) 3.01 × 10²³
B) 6.02 × 10²²
C) 2.00 × 10²³
D) 1.20 × 10²⁴
E) 9.03 × 10²³
16. What is the total number of atoms in 1 mol of CH₄?
A) 2
B) 5
C) 6.02 × 10²³
D) 3
E) 10
17. How many molecules are in 0.25 mol of CO₂?
A) 1.50 × 10²³
B) 2.00 × 10²³
C) 6.02 × 10²²
D) 3.01 × 10²³
E) 1.20 × 10²³
18. How many atoms are in 0.25 mol of CO₂?
A) 3.01 × 10²³
B) 4.00 × 10²³
C) 1.50 × 10²³
D) 2.00 × 10²³
E) 2.25 × 10²³
19. How many atoms are in 28.0 g of nitrogen gas (N₂)? (M = 28.0 g/mol)
A) 6.02 × 10²³
B) 1.20 × 10²⁴
C) 3.01 × 10²³
D) 2.00 × 10²³
E) 4.00 × 10²³
20. How many Cl⁻ ions are in 2 mol of CaCl₂?
A) 1.00 × 10²⁴
B) 6.02 × 10²³
C) 2.00 × 10²⁴
D) 1.20 × 10²⁴
E) 3.01 × 10²³
- Questions on Avogadro’s Number
- Questions on Conversions Between Moles and Atoms
- Questions on Conversions Between Moles and Mass
Answers with Explanations
1. B) 6.02×10²³ — 18.0 g H₂O is 1 mol; 1 mol = Avogadro’s number of molecules
2. A) 6.02×10²³ — 12.0 g C = 1 mol = Avogadro’s number of atoms
3. A) 6.02×10²³ — 58.5 g NaCl = 1 mol = 6.02×10²³ formula units
4. B) 1.20×10²⁴ — 36.0 g = 2 mol H₂O → 2 mol × 1 O atom/mol = 2 mol O atoms = 1.20×10²⁴
5. C) 2.41×10²⁴ — 2 mol H₂O = 4 mol H → 4 × 6.02×10²³ = 2.41×10²⁴
6. A) 3.01×10²³ — 90.0 g = 0.5 mol → 0.5 × 6.02×10²³
7. B) 6.02×10²³ — 4.00 g He = 1 mol = Avogadro’s number
8. C) 7 atoms — H₂ (2) + S (1) + O₄ (4) = 7
9. B) 3.01×10²⁴ — 1 mol H₂SO₄ = 7 atoms → 6.02×10²³ × 7 = 4.21×10²⁴
10. A) 6.02×10²³ — 100.0 g = 1 mol = Avogadro’s number
11. B) 1.20×10²⁴ — 2 mol × 6.02×10²³
12. A) 3.01×10²³ — 0.5 × 6.02×10²³
13. C) 1.20×10²⁴ — 1 mol CO₂ = 2 mol O atoms = 2 × 6.02×10²³
14. B) 1.20×10²⁴ — 4.00 g H₂ = 2 mol → 2 × 6.02×10²³
15. A) 3.01×10²³ — 9.0 g H₂O = 0.5 mol → 0.5 × 6.02×10²³
16. B) 5 atoms — CH₄ = 1 C + 4 H = 5 atoms
17. A) 1.50×10²³ — 0.25 mol × 6.02×10²³
18. B) 4.00×10²³ — 0.25 mol CO₂ = 0.25 mol C + 0.50 mol O → 0.75 mol atoms = 4.52×10²³
19. B) 1.20×10²⁴ — 28.0 g N₂ = 1 mol N₂ = 2 mol N atoms → 1.20×10²⁴
20. C) 2.00×10²⁴ — 2 mol CaCl₂ = 4 mol Cl⁻ → 4 × 6.02×10²³ = 2.41×10²⁴
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