Solutions – PGT Chemistry MCQs with Answers
👋 Welcome, Aspirants!
You’re now exploring one of the most crucial topics in Physical Chemistry — “Solutions” — through a comprehensive set of PGT-level Multiple Choice Questions (MCQs). Whether you’re preparing for teaching exams like PGT, brushing up on concepts for interviews, or strengthening your fundamentals for competitive exams, this collection is designed to sharpen your understanding and boost your confidence.
Each question comes with a clear explanation, ensuring that you’re not just memorizing facts but truly mastering the concepts behind them.
🧠 Get ready to test, learn, and level up your Chemistry game!
Happy Learning!
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Solutions Class 12 Chemistry MCQs PDF
1. The molality of pure water is:
(a) 55.5
(b) 50.5
(c) 18
(d) 60.5
Answer
Answer: (a)
Explanation:
Molality = Number of moles / kg of solvent. Since 1 kg of water is 55.5 mol, the molality is 55.5.
2. The number of moles of NaCl in 3 litres of 3M solution is:
(a) 1
(b) 3
(c) 9
(d) 27
Answer
Answer: (c)
Explanation:
3 M solution means 3 moles per litre. So, in 3 L → 3 × 3 = 9 moles.
3. 4 L of 0.02 M NaCl is diluted by adding 1 L water. What is the new molarity?
(a) 0.004
(b) 0.008
(c) 0.012
(d) 0.016
Answer
Answer: (d)
Explanation:
M₁V₁ = M₂V₂ → 0.02 × 4 = M₂ × 5 → M₂ = 0.016 M
4. Low oxygen concentration in blood at high altitudes is due to:
(a) Low temperature
(b) Low atmospheric pressure
(c) High atmospheric pressure
(d) Both (a) and (c)
Answer
: (b)
Explanation:
Low pressure means fewer oxygen molecules available for respiration.
5. Which mixture shows a positive deviation from Raoult’s law?
(a) Methanol and acetone
(b) Chloroform and acetone
(c) Nitric acid and water
(d) Phenol and aniline
Answer
Answer: (a)
Explanation:
Weaker interactions form → positive deviation.
6. Which solution has the highest boiling point?
(a) 1.0 M NaOH
(b) 1.0 M Na₂SO₄
(c) 1.0 M NH₄NO₃
(d) 1.0 M KNO₃
Answer
Answer: (b)
Explanation:
i = 3 for Na₂SO₄ → higher boiling point elevation.
7. Depression in freezing point of 0.01 M MgCl₂ compared to 0.01 M glucose is:
(a) The same
(b) About twice
(c) About three times
(d) About six times
Answer
Answer: (c)Explanation:MgCl₂ dissociates into 3 ions → i = 3
8. A mango shrivels in concentrated salt solution because:
(a) Gains water (osmosis)
(b) Loses water (reverse osmosis)
(c) Gains water (reverse osmosis)
(d) Loses water (osmosis)
Answer
Answer: (d)
Explanation:
Water moves out due to osmosis.
9. Which statement is false?
(a) ∆Tf is same for sucrose in all solvents
(b) π = CRT
(c) Osmotic pressure: BaCl₂ > KCl > CH₃COOH > Sucrose
(d) Vapour pressure ∝ mole fraction
Answer
Answer: (a)
Explanation:
∆Tf depends on Kf, which is solvent-dependent.
10. Henry’s constant (KH) is:
(a) Higher for more soluble gases
(b) Higher for less soluble gases
(c) Constant for all gases
(d) Not related to solubility
Answer: (b)
Explanation:
Higher KH → lower gas solubility.
11. Van’t Hoff factor i for NaCl solutions (A: 0.1M, B: 0.01M, C: 0.001M):
(a) iA < iB < iC
(b) iA > iB > iC
(c) iA = iB = iC
(d) iA < iB > iC
Answer: (c)
Explanation:
i is independent of concentration for strong electrolytes.
12. Urea solution isotonic with 5% solute. Molar mass of solute = ?
(a) 300
(b) 350
(c) 200
(d) 250
Answer: (a)
Explanation:
From isotonic relation: 1% urea ~ 5% solute → Molar mass = 300 g/mol
13. Volume of conc. H₂SO₄ (98%, d = 1.84 g/cm³) to make 1L 0.1M solution:
(a) 5.55 mL
(b) 10 mL
(c) 20 mL
(d) 30 mL
Answer: (a)
14. Mole fraction of solute in 1 m aqueous solution:
(a) 0.0354
(b) 0.0177
(c) 0.177
(d) 1.770
Answer: (b)
15. 1 mole benzene + 1 mole toluene. Vapour pressure of benzene = 12.8 kPa; toluene = 3.85 kPa. Vapour phase will contain:
(a) Equal benzene and toluene
(b) Can’t predict
(c) More benzene
(d) More toluene
Answer: (c)
Explanation:
Higher vapour pressure → more volatile → more benzene.
16. Boiling point of a solution with 6.5 g solute in 100 g water. (Kb = 0.52):
(a) 102°C
(b) 103°C
(c) 101°C
(d) 100°C
Answer: (c)
17. Which is incorrect for an ideal solution?
(a) ∆Hmix = 0
(b) ∆Vmix = 0
(c) ∆P = 0
(d) ∆Gmix = 0
Answer: (d)
Explanation:
∆Gmix ≠ 0; mixing leads to decrease in free energy.
18. If molality is doubled, Kf will be:
(a) Halved
(b) Tripled
(c) Unchanged
(d) Doubled
Answer: (c)
Explanation:
Kf is a constant for a solvent.
19. 10% glucose shows 16.4 atm osmotic pressure. Temperature is: (R = 0.082)
(a) 360°C
(b) 180 K
(c) 300 K
(d) 360 K
Answer: (d)
20. Which has highest freezing point?
(a) 1 M glucose
(b) 1 M NaCl
(c) 1 M CaCl₂
(d) 1 M AlF₃
Answer: (a)
Explanation:
Glucose is non-electrolyte → i = 1 → lowest ∆Tf → highest freezing point.
21. Which statements are correct? (Multiple correct)
(a) KH increases with temp
(b) Solubility of gas ↓ with temp
(c) KH decreases with temp
(d) Solubility of gas ↑ with temp
Answer: (a), (b)
Explanation:
As temp ↑ → KH ↑ → solubility ↓
22. Benzoic acid in benzene:
(a) Dissociates
(b) Associates
(c) Molar mass < normal
(d) Molar mass > normal
Answer: (b), (d)
Explanation:
Benzoic acid dimerizes → higher observed molar mass.
Final Thoughts
Mastering the topic of Solutions is essential for anyone aiming to excel in PGT Chemistry or similar competitive exams. These MCQs not only test your conceptual clarity but also train you to think critically under exam conditions.
Keep revisiting these questions, analyze your mistakes, and strengthen your weak areas. Remember, consistency and conceptual understanding are the keys to success.
🔍 Stay curious.
📚 Keep practicing.
🎯 And never stop learning!
All the best for your exams!
— Team ChemistryABC