Chemistry MCQ Practice 22 — Science Foundation Course for Class 11 & 12

1. The process used to separate a mixture of o-nitrophenol and p-nitrophenol is:

(a) Distillation (b) Steam distillation (c) Fractional distillation (d) Crystallisation

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Correct Answer: (b) Steam distillation

Explanation:
o-nitrophenol is steam volatile due to intramolecular H-bonding

2. The number of π-electrons in benzene according to Huckel's rule is:

(a) 4 (b) 6 (c) 8 (d) 10

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Correct Answer: (b) 6

Explanation:
4n + 2 = 6 (n=1) → aromatic

3. Which of the following is a pseudo first order reaction?

(a) Hydrolysis of ester in acid medium (b) Decomposition of HI (c) Inversion of cane sugar (d) Both (a) and (c)

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Correct Answer: (d) Both (a) and (c)

Explanation:
Water is in large excess, so order becomes pseudo first

4. The coordination number of Na⁺ in NaCl crystal is:

(a) 4 (b) 6 (c) 8 (d) 12

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Correct Answer: (b) 6

Explanation:
Rock salt structure (FCC) — each Na⁺ surrounded by 6 Cl⁻

5. The IUPAC name of the compound with formula (CH₃)₂CHCH₂CH₂Br is:

(a) 1-Bromo-3-methylbutane (b) 1-Bromo-2-methylbutane (c) 1-Bromopentane (d) 2-Bromo-3-methylbutane

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Correct Answer: (a) 1-Bromo-3-methylbutane

Explanation:
Longest chain with lowest number to Br

6. Which of the following has the highest boiling point?

(a) n-Pentane (b) 2-Methylbutane (c) 2,2-Dimethylpropane (d) All have same

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Correct Answer: (a) n-Pentane

Explanation:
Straight chain has maximum surface area → stronger van der Waals forces

7. The half-life period of a radioactive element is 140 days. After 560 days, the fraction of the element left is:

(a) 1/2 (b) 1/4 (c) 1/8 (d) 1/16

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Correct Answer: (d) 1/16

Explanation:
560 / 140 = 4 half-lives → (1/2)⁴ = 1/16

8. The refining method used for zinc is:

(a) Mond process (b) Electrolytic refining (c) Distillation (d) Zone refining

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Correct Answer: (c) Distillation

Explanation:
Zinc is volatile and purified by distillation

9. The polymer used in non-stick cookware is:

(a) PVC (b) Teflon (c) Bakelite (d) Nylon

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Correct Answer: (b) Teflon

Explanation:
Polytetrafluoroethylene (PTFE)

10. The vitamin required for carboxylation reactions is:

(a) Vitamin B₁₂ (b) Biotin (c) Folic acid (d) Vitamin K

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Correct Answer: (b) Biotin

Explanation:
Biotin is coenzyme for carboxylase enzymes