Chemistry MCQ Practice 25 — Science Foundation Course for Class 11 & 12

1. The abnormal colligative property observed in solution of electrolytes is due to:

(a) Association (b) Dissociation (c) Both association and dissociation (d) None of these

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Correct Answer: (b) Dissociation

Explanation:
Electrolytes dissociate into ions, increasing the number of particles (van't Hoff factor > 1)

2. The complex ion [Fe(CN)₆]⁴⁻ is:

(a) Inner orbital complex (b) Outer orbital complex (c) High spin complex (d) Paramagnetic

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Correct Answer: (a) Inner orbital complex

Explanation:
d²sp³ hybridisation (low spin) with strong field CN⁻ ligand

3. Which of the following is a thermosetting polymer?

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

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Correct Answer: (c) Bakelite

Explanation:
Phenol-formaldehyde resin is thermosetting

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 the compound CH₃-CH₂-CH(CH₃)-CH₂-CH₂-CH₃ is:

(a) 3-Methylhexane (b) 2-Methylhexane (c) 4-Methylhexane (d) 2-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 acidic strength is:

(a) CH₃COOH > ClCH₂COOH > Cl₂CHCOOH > Cl₃CCOOH (b) Cl₃CCOOH > Cl₂CHCOOH > ClCH₂COOH > CH₃COOH (c) ClCH₂COOH > CH₃COOH > Cl₂CHCOOH > Cl₃CCOOH (d) Cl₂CHCOOH > Cl₃CCOOH > ClCH₂COOH > CH₃COOH

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Correct Answer: (b) Cl₃CCOOH > Cl₂CHCOOH > ClCH₂COOH > CH₃COOH

Explanation:
More -I effect of Cl increases acidity

7. The half-life of a radioactive element is 200 days. After 600 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: (c) 1/8

Explanation:
600 / 200 = 3 half-lives → (1/2)³ = 1/8

8. The process used for concentration of sulphide ores is:

(a) Froth flotation (b) Magnetic separation (c) Leaching (d) Distillation

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Correct Answer: (a) Froth flotation

Explanation:
Sulphide ores are preferentially wetted by oil

9. The polymer used in making artificial skin is:

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

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Correct Answer: (b) Polyurethane

Explanation:
Polyurethane is used in artificial skin and biomedical applications

10. The co-enzyme required for transamination reactions is:

(a) Pyridoxal phosphate (Vitamin B₆) (b) Biotin (c) Thiamine pyrophosphate (d) FAD

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Correct Answer: (a) Pyridoxal phosphate (Vitamin B₆)

Explanation:
PLP is coenzyme for aminotransferase enzymes