31. What is the weight percent of solute in a solution containing 25 g of solute and 75 g of solvent?
a) 25%
b) 50%
c) 33%
d) 20%
Answer: a) 25%
32. Which of the following terms is dimensionless?
a) Molarity
b) Molality
c) Mole fraction
d) Normality
Answer: c) Mole fraction
Explanation:
Mole fraction is a ratio of moles of solute to the total moles in the solution, so it has no units and is dimensionless.
33. What is the mole fraction of solute in a solution that contains 2 moles of solute and 8 moles of solvent?
a) 0.2
b) 0.25
c) 0.4
d) 0.8
Answer: b) 0.25
34. What will be the molality of a solution prepared by dissolving 9.8 g of H₂SO₄ in 250 g of water?
(Molecular weight of H₂SO₄ = 98 g/mol)
a) 0.1 mol/kg
b) 0.2 mol/kg
c) 0.4 mol/kg
d) 0.5 mol/kg
Answer: b) 0.4 mol/kg
35. If the mole fraction of water in a solution is 0.75, what is the mole fraction of the solute?
a) 0.75
b) 0.50
c) 0.25
d) 0.10
Answer: c) 0.25
Explanation:
In a binary solution, the sum of mole fractions of the solute and solvent is 1.
Mole fraction of solute = 1−0.75=0.25
36. A 10% (w/w) NaCl solution contains how many grams of NaCl in 200 g of the solution?
a) 10 g
b) 20 g
c) 30 g
d) 40 g
Answer: b) 20 g
37. Which of the following concentration terms is used when dealing with electrolytes?
a) Molarity
b) Molality
c) Normality
d) Mole fraction
Answer: c) Normality
Explanation:
Normality is often used for electrolytes because it accounts for the equivalents of reactive ions (like H⁺ or OH⁻) per liter of solution, which is important for titrations and reactions involving acids and bases.
38. Which of the following solutions has the highest concentration if all contain the same number of moles of solute?
a) 1 L of solution
b) 2 L of solution
c) 0.5 L of solution
d) 5 L of solution
Answer: c) 0.5 L of solution
Explanation:
Molarity is defined as the number of moles of solute per liter of solution. The smaller the volume of the solution, the higher the molarity. So, the 0.5 L solution will have the highest concentration.
39. If 5 moles of solute are dissolved in 10 kg of solvent, what is the molality of the solution?
a) 0.1 mol/kg
b) 0.5 mol/kg
c) 1 mol/kg
d) 2 mol/kg
Answer: b) 0.5 mol/kg
40. A solution of 1 M HCl has a density of 1.1 g/mL. What is the molality of this solution?
(Molecular weight of HCl = 36.5 g/mol)
a) 0.98 mol/kg
b) 1.0 mol/kg
c) 1.1 mol/kg
d) 1.5 mol/kg
Answer: a) 0.98 mol/kg
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