81. What is the normality of a solution containing 40 g of NaOH in 1 L of solution?
(Molecular weight of NaOH = 40 g/mol)
a) 0.5 N
b) 1 N
c) 2 N
d) 4 N
Answer: b) 1 N
82. If 58.5 g of NaCl is dissolved in 500 mL of solution, what is the molarity?
(Molecular weight of NaCl = 58.5 g/mol)
a) 1 M
b) 2 M
c) 3 M
d) 4 M
Answer: b) 2 M
83. A solution has a density of 1.12 g/mL. If the molarity of the solution is 1 M and the solute has a molar mass of 60 g/mol, what is the molality of the solution?
a) 0.89 mol/kg
b) 1 mol/kg
c) 1.12 mol/kg
d) 2 mol/kg
Answer: a) 0.89 mol/kg
84. Which of the following is independent of temperature?
a) Molarity
b) Molality
c) Normality
d) Volume percent
Answer: b) Molality
Explanation:
Molality is based on the mass of the solvent, which does not change with temperature, unlike molarity or normality which depend on the volume of the solution.
85. A solution contains 2 moles of HCl in 500 mL of solution. What is its molarity?
a) 0.5 M
b) 1 M
c) 2 M
d) 4 M
Answer: d) 4 M
86. What is the molality of a solution prepared by dissolving 5 g of NaOH in 200 g of water?
(Molecular weight of NaOH = 40 g/mol)
a) 0.625 mol/kg
b) 1 mol/kg
c) 0.5 mol/kg
d) 0.125 mol/kg
Answer: a) 0.625 mol/kg
87. What is the mole fraction of a solute in a solution where 2 moles of solute are dissolved in 8 moles of solvent?
a) 0.1
b) 0.2
c) 0.25
d) 0.8
Answer: b) 0.2
88. If 1 mole of glucose is dissolved in 1 kg of water, the freezing point depression of the solution is:
(K_f for water = 1.86°C kg/mol)
a) 1.86°C
b) 3.72°C
c) 5.58°C
d) 7.44°C
Answer: a) 1.86°C
Explanation:
Freezing point depression, ΔTf=Kf×molality
Molality = 1 mol/kg
ΔTf=1.86 °C×1=1.86 °C
89. Which of the following solutions will have the lowest boiling point?
a) 1 M NaCl
b) 1 M glucose
c) 1 M AlCl₃
d) 1 M K₂SO₄
Answer: b) 1 M glucose
Explanation:
Boiling point elevation depends on the number of particles. Since glucose does not dissociate in solution, it has the fewest particles, leading to the lowest boiling point elevation.
90. What is the molality of a solution prepared by dissolving 10 g of glucose (C₆H₁₂O₆) in 90 g of water?
(Molecular weight of glucose = 180 g/mol)
a) 0.5 mol/kg
b) 0.62 mol/kg
c) 1 mol/kg
d) 1.5 mol/kg
Answer: b) 0.62 mol/kg
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