- The molar mass of calcium phosphate (Ca₃(PO₄)₂) is:
a) 100 g/mol
b) 220 g/mol
c) 310 g/mol
d) 250 g/mol
Answer: c) 310 g/mol
Explanation: Molar mass = (3 × 40.08) + (2 × (30.97 + (4 × 16))) = 310.18 g/mol.
- How many grams are in 1.5 moles of H₂SO₄ (Molar mass = 98 g/mol)?
a) 147 g
b) 150 g
c) 120 g
d) 130 g
Answer: a) 147 g
Explanation: 1.5 moles × 98 g/mol = 147 g.
- In the reaction: N₂ + 3H₂ → 2NH₃, how many moles of hydrogen are needed for 1 mole of nitrogen?
a) 1 mole
b) 2 moles
c) 3 moles
d) 4 moles
Answer: c) 3 moles
Explanation: The stoichiometry shows that 1 mole of N₂ requires 3 moles of H₂.
- The volume occupied by 4 moles of an ideal gas at STP is:
a) 100 L
b) 89.6 L
c) 90 L
d) 89.7 L
Answer: a) 89.6 L
Explanation: 4 moles × 22.4 L/mole = 89.6 L.
- The number of moles in 80 g of Ca(OH)₂ (Molar mass = 74 g/mol) is:
a) 1.08 moles
b) 1.15 moles
c) 2.00 moles
d) 0.90 moles
Answer: a) 1.08 moles
Explanation: 80 g ÷ 74 g/mol ≈ 1.08 moles.
- How many grams are in 0.8 moles of NaHCO₃ (Molar mass = 84 g/mol)?
a) 66.4 g
b) 65 g
c) 70 g
d) 72 g
Answer: a) 67.2 g
Explanation: 0.8 moles × 84 g/mol = 67.2 g.
- The molar mass of sulfuric acid (H₂SO₄) is:
a) 96 g/mol
b) 98 g/mol
c) 100 g/mol
d) 95 g/mol
Answer: b) 98 g/mol
Explanation: Molar mass = 2 × 1.01 + 32.07 + 4 × 16.00 = 98.09 g/mol.
- The mass of 1 mole of CO₂ (Molar mass = 44 g/mol) is:
a) 40 g
b) 42 g
c) 44 g
d) 46 g
Answer: c) 44 g
Explanation: 1 mole × 44 g/mol = 44 g.
- How many moles are in 90 g of H₂O₂ (Molar mass = 34 g/mol)?
a) 2.5 moles
b) 3.0 moles
c) 1.5 moles
d) 2.0 moles
Answer: b) 2.65 moles
Explanation: 90 g ÷ 34 g/mol ≈ 2.65 moles.
- The molar mass of potassium hydroxide (KOH) is:
a) 100 g/mol
b) 92 g/mol
c) 80 g/mol
d) 75 g/mol
Answer: b) 56.11 g/mol
Explanation: Molar mass = 39.10 + 16.00 + 1.01 = 56.11 g/mol.
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