- The molar mass of potassium permanganate (KMnO₄) is:
a) 158 g/mol
b) 160 g/mol
c) 170 g/mol
d) 180 g/mol
Answer: a) 158 g/mol
Explanation: Molar mass = 39.10 + 54.94 + (4 × 16) = 158.04 g/mol.
- How many grams are in 2.5 moles of NaCl (Molar mass = 58.5 g/mol)?
a) 130 g
b) 140 g
c) 145 g
d) 150 g
Answer: a) 146.25 g
Explanation: 2.5 moles × 58.5 g/mol = 146.25 g.
- The number of moles in 1 g of NaCl is:
a) 0.01 moles
b) 0.02 moles
c) 0.03 moles
d) 0.04 moles
Answer: b) 0.017 moles
Explanation: 1 g ÷ 58.5 g/mol ≈ 0.017 moles.
- The mass of 3 moles of H₂ (Molar mass = 2 g/mol) is:
a) 4 g
b) 5 g
c) 6 g
d) 8 g
Answer: c) 6 g
Explanation: 3 moles × 2 g/mol = 6 g.
- In the reaction: 2H₂ + O₂ → 2H₂O, how many moles of water are produced from 2 moles of hydrogen?
a) 1 mole
b) 2 moles
c) 3 moles
d) 4 moles
Answer: b) 2 moles
Explanation: The stoichiometry indicates that 2 moles of H₂ produce 2 moles of H₂O.
- The volume occupied by 10 moles of an ideal gas at STP is:
a) 200 L
b) 220 L
c) 240 L
d) 224 L
Answer: a) 224 L
Explanation: 10 moles × 22.4 L/mole = 224 L.
- How many grams are in 0.4 moles of C₆H₁₂O₆ (Molar mass = 180 g/mol)?
a) 60 g
b) 70 g
c) 72 g
d) 80 g
Answer: c) 72 g
Explanation: 0.4 moles × 180 g/mol = 72 g.
- The molar mass of barium chloride (BaCl₂) is:
a) 137 g/mol
b) 165 g/mol
c) 200 g/mol
d) 250 g/mol
Answer: b) 208 g/mol
Explanation: Molar mass = 137.33 + (2 × 35.45) = 208.23 g/mol.
- The number of moles in 300 g of CaCO₃ (Molar mass = 100 g/mol) is:
a) 1.0 mole
b) 2.0 moles
c) 3.0 moles
d) 4.0 moles
Answer: b) 3.0 moles
Explanation: 300 g ÷ 100 g/mol = 3.0 moles.
- How many moles are in 50 g of Al₂O₃ (Molar mass = 102 g/mol)?
a) 0.4 moles
b) 0.5 moles
c) 0.6 moles
d) 0.7 moles
Answer: b) 0.49 moles
Explanation: 50 g ÷ 102 g/mol ≈ 0.49 moles.
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