Physical Chemistry MCQs (1–25)

 

Physical Chemistry MCQs (1–25)

1. Which gas will diffuse fastest at the same temperature?
   a) H₂ b) O₂ c) N₂ d) CO₂

2. The molarity of a solution is 2 M and its density is 1.2 g/mL. Its molality is:
   a) 1.5 m b) 1.2 m c) 2 m d) 0.8 m

3. 0.01 M HCl solution has a pH of:
   a) 2 b) 3 c) 1 d) 4

4. Which reaction is first order?
   a) 2A → B, rate ∝ [A]²
   b) A → B, rate ∝ [A]
   c) A + B → C, rate ∝ [A][B]
   d) None

5. Which of the following is true for colligative properties?
   a) Depend on nature of solute b) Depend on number of solute particles
   c) Depend on volume of solution d) Depend on solvent polarity

6. The van der Waals equation corrects for:
   a) Molecular volume only
   b) Intermolecular forces only
   c) Molecular volume and intermolecular forces
   d) Pressure and temperature

7. The Gibbs free energy change is negative for:
   a) Spontaneous reaction b) Non-spontaneous reaction
   c) Reversible reaction d) Endothermic reaction

8. The half-life of a first-order reaction is 138 min. The rate constant is:
   a) 0.005 min⁻¹ b) 0.01 min⁻¹ c) 0.02 min⁻¹ d) 0.03 min⁻¹

9. Degree of dissociation α of 0.1 M CH₃COOH (Ka = 1.8 × 10⁻⁵) is approximately:
   a) 0.013 b) 0.1 c) 0.05 d) 0.5

10. Freezing point depression of 0.1 m NaCl (Kf = 1.86 K kg mol⁻¹) is:
    a) 0.186 K b) 0.372 K c) 0.093 K d) 0.5 K

11. Work done in isothermal expansion of 2 L → 6 L against 1 atm:
    a) 136 J b) 273 J c) 546 J d) 100 J

12. Osmotic pressure of 1 M glucose at 25°C is:
    a) 22.4 atm b) 24.45 atm c) 20 atm d) 25 atm

13. ΔH for N₂ + 3H₂ → 2NH₃ is -92 kJ/mol. Reaction is:
    a) Endothermic b) Exothermic c) Neutral d) Cannot say

14. Kc = 4, Δn = 2. Kp = ?
    a) 16 b) 32 c) 64 d) 128

15. Which is correct for ionic product of water?
    a) Kw = [H⁺][OH⁻] b) Kw = [H⁺] + [OH⁻]
    c) Kw = [H⁺]² d) Kw = [OH⁻]²

16. pOH of 10⁻³ M NaOH solution:
    a) 1 b) 3 c) 11 d) 13

17. Which gas law explains solubility of gases in liquids?
    a) Boyle’s law b) Henry’s law c) Raoult’s law d) Dalton’s law

18. Reaction order of 2A → B, rate doubles when [A] doubles:
    a) 1 b) 2 c) 0 d) ½

19. Adding inert gas at constant volume:
    a) Increases equilibrium constant b) Decreases equilibrium constant
    c) No effect on equilibrium constant d) Shifts equilibrium

20. Partial molar volume of a component is:
    a) Volume per mole of pure substance
    b) Contribution of component to solution volume
    c) Total solution volume d) Volume at STP

21. Freezing point of water at 1 atm:
    a) 0°C b) 100°C c) -273°C d) 25°C

22. Viscosity of liquid with temperature:
    a) Increases b) Decreases c) Constant d) Unpredictable

23. Gas evolved when NaHCO₃ reacts with HCl:
    a) O₂ b) CO₂ c) H₂ d) N₂

24. Effect of pressure on N₂ + 3H₂ ⇌ 2NH₃:
    a) Shifts forward b) Shifts backward c) No effect d) Decreases rate

25. Entropy change in reversible isothermal expansion:
    a) ΔS = 0 b) ΔS > 0 c) ΔS < 0 d) Cannot say

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Inorganic Chemistry MCQs (26–50)

26. Atomic number of oxygen:
    a) 6 b) 8 c) 16 d) 12

27. Chromate ion formula:
    a) CrO₄²⁻ b) Cr₂O₇²⁻ c) CrO₃ d) Cr³⁺

28. Number of valence electrons in P:
    a) 3 b) 5 c) 7 d) 8

29. Noble gas configuration of K⁺:
    a) [Ar] b) [Ne] c) [Kr] d) [Xe]

30. Common oxidation state of Mn in KMnO₄:
    a) +2 b) +3 c) +4 d) +7

31. Which is amphoteric?
    a) Al₂O₃ b) Na₂O c) MgO d) K₂O

32. Ion with unpaired electrons:
    a) Na⁺ b) Fe³⁺ c) Cl⁻ d) Mg²⁺

33. Hard water contains:
    a) Na⁺, K⁺ b) Ca²⁺, Mg²⁺ c) H⁺, OH⁻ d) Cl⁻, Br⁻

34. Which is a strong acid?
    a) HClO b) HClO₄ c) H₂CO₃ d) CH₃COOH

35. Which is a strong base?
    a) NH₄OH b) NaOH c) CH₃NH₂ d) Al(OH)₃

36. Chlorine belongs to group:
    a) 16 b) 17 c) 18 d) 15

37. Element with maximum electronegativity:
    a) F b) O c) Cl d) N

38. Oxide of N which is neutral:
    a) NO b) N₂O₅ c) NO₂ d) N₂O

39. Sulphur oxidation state in H₂SO₄:
    a) +4 b) +6 c) +2 d) 0

40. Which halogen forms hypo acid?
    a) F b) Cl c) Br d) I

41. Number of d-electrons in Fe³⁺:
    a) 5 b) 6 c) 4 d) 3

42. Which is paramagnetic?
    a) Na⁺ b) O₂ c) Mg²⁺ d) Cl⁻

43. Electronic configuration of Cr:
    a) [Ar]3d⁴4s² b) [Ar]3d⁵4s¹ c) [Ar]3d³4s² d) [Ar]3d⁶4s²

44. Which alkali metal is least reactive?
    a) Li b) Na c) K d) Cs

45. Ionization energy increases:
    a) Left → Right in a period b) Top → Bottom in a group
    c) Both a & b d) None

46. Most acidic oxide:
    a) CO₂ b) SO₂ c) Na₂O d) MgO

47. Which element shows allotropy?
    a) P b) O₂ c) C d) All of these

48. Transition metal with 21 electrons:
    a) Sc b) Ti c) V d) Cr

49. Ionic radius of Na⁺ is:
    a) Smaller than Na b) Larger than Na
    c) Equal to Na d) Cannot say

50. Amphoteric hydroxide:
    a) Zn(OH)₂ b) NaOH c) KOH d) Ba(OH)₂