Chemistry MCQ Practice 28 — Science Foundation Course for Class 11 & 12

1. A solution containing 18 g of glucose (molar mass 180) in 100 g of water has vapour pressure 17.5 mm Hg at 20°C. The vapour pressure of pure water at 20°C is:

(a) 17.5 mm Hg (b) 18.0 mm Hg (c) 17.0 mm Hg (d) 18.5 mm Hg

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Correct Answer: (b) 18.0 mm Hg

Explanation:
Relative lowering = (P° - P)/P° = mole fraction of solute → P° = 18.0 mm Hg

2. The magnetic moment of [NiCl₄]²⁻ is:

(a) 0 BM (b) 1.73 BM (c) 2.83 BM (d) 3.87 BM

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Correct Answer: (c) 2.83 BM

Explanation:
Ni ²⁺ is d⁸, tetrahedral, two unpaired electrons → √8 = 2.83 BM

3. Which of the following is a linear polymer?

(a) Bakelite (b) Nylon-6,6 (c) Melamine-formaldehyde (d) Phenol-formaldehyde

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Correct Answer: (b) Nylon-6,6

Explanation:
Nylon-6,6 is a linear condensation polymer

4. The disease caused by deficiency of Vitamin B₁₂ is:

(a) Beriberi (b) Scurvy (c) Pernicious anaemia (d) Rickets

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Correct Answer: (c) Pernicious anaemia

Explanation:
Vitamin B₁₂ deficiency leads to pernicious anaemia

5. The IUPAC name of CH₃-CH₂-CH(CH₃)-CH₂-CH₂-CH₃ is:

(a) 3-Methylhexane (b) 2-Methylhexane (c) 4-Methylhexane (d) 3-Ethylpentane

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Correct Answer: (a) 3-Methylhexane

Explanation:
Longest chain of 6 carbons with methyl at position 3

6. The correct order of boiling points is:

(a) HF > HCl > HBr > HI (b) HI > HBr > HCl > HF (c) HF > HI > HBr > HCl (d) HCl > HBr > HI > HF

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Correct Answer: (c) HF > HI > HBr > HCl

Explanation:
HF has strong hydrogen bonding

7. For a second order reaction, the half-life is proportional to:

(a) 1/[A]₀ (b) [A]₀ (c) [A]₀² (d) Independent of concentration

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Correct Answer: (a) 1/[A]₀

Explanation:
t₁/₂ = 1 / (k [A]₀) for second order

8. The process used for concentration of bauxite ore is:

(a) Froth flotation (b) Magnetic separation (c) Leaching (Bayer's process) (d) Distillation

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Correct Answer: (c) Leaching (Bayer's process)

Explanation:
Bauxite is concentrated by digestion with NaOH

9. The polymer used in making contact lenses is:

(a) Perspex (b) Silicone (c) Teflon (d) Nylon

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Correct Answer: (a) Perspex

Explanation:
Polymethyl methacrylate (PMMA) is used for contact lenses

10. The enzyme that digests fats is:

(a) Lipase (b) Amylase (c) Pepsin (d) Maltase

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Correct Answer: (a) Lipase

Explanation:
Lipase hydrolyses fats into fatty acids and glycerol