21. Which of the following is a concentration term that depends on the mass of the solvent but not on the volume of the solution?
a) Molarity
b) Molality
c) Normality
d) Weight percent
Answer: b) Molality
Explanation:
Molality is defined as the number of moles of solute per kilogram of solvent, so it is independent of the volume of the solution and depends only on the mass of the solvent.
22. What is the molality of a solution in which 5 moles of solute are dissolved in 2 kg of solvent?
a) 2.5 mol/kg
b) 1.5 mol/kg
c) 5 mol/kg
d) 10 mol/kg
Answer: a) 2.5 mol/kg
23. A solution is prepared by dissolving 2 mol of solute in 500 mL of solution. What is the molarity of the solution?
a) 4 M
b) 2 M
c) 1 M
d) 0.5 M
Answer: a) 4 M
24. The mole fraction of solute in a binary solution is 0.2. What is the mole fraction of the solvent?
a) 0.2
b) 0.3
c) 0.8
d) 1.0
Answer: c) 0.8
25. A solution of glucose is 10% (w/w). What is the mass of glucose in 500 g of this solution?
a) 50 g
b) 10 g
c) 100 g
d) 20 g
Answer: a) 50 g
26. If the molarity of a solution is 3 M, what is the number of moles of solute present in 2 L of the solution?
a) 3 mol
b) 6 mol
c) 1.5 mol
d) 0.5 mol
Answer: b) 6 mol
Explanation:
Molarity = moles of solute / volume of solution in liters
Moles of solute = Molarity × Volume
Moles of solute = 3 M×2 L=6 mol
27. If 50 mL of 0.5 M HCl is diluted to 250 mL, what will be the new molarity of the solution?
a) 0.1 M
b) 0.2 M
c) 0.5 M
d) 1 M
Answer: a) 0.1 M
28. What is the mole fraction of water in a solution containing 18 g of water and 46 g of ethanol?
(Molecular weight of water = 18 g/mol, ethanol = 46 g/mol)
a) 0.5
b) 0.33
c) 0.67
d) 0.75
Answer: a) 0.5
29. Which of the following solutions has the highest molality?
a) 1 M solution of glucose
b) 1 M solution of NaCl
c) 1 M solution of H₂SO₄
d) 1 M solution of KCl
Answer: a) 1 M solution of glucose
Explanation:
Molality depends on the number of moles of solute per kg of solvent. Glucose has a higher molar mass compared to NaCl, H₂SO₄, and KCl, so for the same molarity, the solution with the largest molecular mass will have the highest molality because it results in fewer moles per liter of solution, which means more mass of solvent.
30. The normality of 1 M H₂SO₄ solution is:
a) 1 N
b) 2 N
c) 0.5 N
d) 0.25 N
Answer: b) 2 N
Explanation:
Normality (N) = Molarity (M) × n-factor
For H₂SO₄, the n-factor is 2 (as it can donate 2 H⁺ ions).
Normality = 1 M×2=2 N
Leave a comment