- How many moles are in 250 g of Fe₂O₃ (Molar mass = 159.7 g/mol)?
a) 1.5 moles
b) 2.0 moles
c) 1.0 mole
d) 3.0 moles
Answer: a) 1.56 moles
Explanation: 250 g ÷ 159.7 g/mol ≈ 1.56 moles.
- What is the volume occupied by 3 moles of an ideal gas at STP?
a) 67.2 L
b) 66.4 L
c) 68.4 L
d) 67.0 L
Answer: a) 67.2 L
Explanation: 3 moles × 22.4 L/mole = 67.2 L.
- The molar mass of sodium sulfate (Na₂SO₄) is:
a) 142 g/mol
b) 150 g/mol
c) 160 g/mol
d) 170 g/mol
Answer: a) 142 g/mol
Explanation: Molar mass = (2 × 22.99) + 32.07 + (4 × 16) = 142.05 g/mol.
- How many grams are in 0.5 moles of KCl (Molar mass = 74.5 g/mol)?
a) 30 g
b) 37.25 g
c) 50 g
d) 70 g
Answer: b) 37.25 g
Explanation: 0.5 moles × 74.5 g/mol = 37.25 g.
- In the reaction 2C + O₂ → 2CO, how many moles of carbon are needed to react with 1 mole of oxygen?
a) 1 mole
b) 2 moles
c) 3 moles
d) 4 moles
Answer: b) 2 moles
Explanation: The reaction indicates that 2 moles of carbon react with 1 mole of oxygen.
- The number of moles in 150 g of C₃H₈ (Molar mass = 44 g/mol) is:
a) 3.0 moles
b) 2.5 moles
c) 4.0 moles
d) 5.0 moles
Answer: b) 3.41 moles
Explanation: 150 g ÷ 44 g/mol ≈ 3.41 moles.
- How many grams are in 2 moles of NH₄Cl (Molar mass = 53.5 g/mol)?
a) 90 g
b) 100 g
c) 105 g
d) 110 g
Answer: c) 107 g
Explanation: 2 moles × 53.5 g/mol = 107 g.
- What is the molar mass of zinc sulfate (ZnSO₄)?
a) 160 g/mol
b) 180 g/mol
c) 200 g/mol
d) 220 g/mol
Answer: b) 161 g/mol
Explanation: Molar mass = 65.38 + 32.07 + (4 × 16) = 161.44 g/mol.
- The mass of 0.75 moles of H₂O (Molar mass = 18 g/mol) is:
a) 13.5 g
b) 12 g
c) 15 g
d) 16 g
Answer: a) 13.5 g
Explanation: 0.75 moles × 18 g/mol = 13.5 g.
- How many moles are in 60 g of AgNO₃ (Molar mass = 170 g/mol)?
a) 0.35 moles
b) 0.25 moles
c) 0.40 moles
d) 0.45 moles
Answer: b) 0.35 moles
Explanation: 60 g ÷ 170 g/mol ≈ 0.35 moles.
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