Chemistry MCQ Practice 23 — Science Foundation Course for Class 11 & 12

1. The elevation in boiling point of a solution is proportional to:

(a) Molality (b) Molarity (c) Mole fraction (d) Mass of solvent

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Correct Answer: (a) Molality

Explanation:
ΔT_b = K_b × m (colligative property depends on molality)

2. Which of the following is a diamagnetic ion?

(a) Cr³⁺ (b) Mn²⁺ (c) Zn ²⁺ (d) Fe²⁺

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Correct Answer: (c) Zn²⁺

Explanation:
Zn²⁺ has completely filled 3d¹⁰ configuration (no unpaired electrons)

3. The polymer used in making bullet-proof vests is:

(a) Nylon-6,6 (b) Kevlar (c) Bakelite (d) Teflon

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Correct Answer: (b) Kevlar

Explanation:
Kevlar is a polyamide with high tensile strength

4. The deficiency of which vitamin causes beriberi?

(a) Vitamin B₁ (b) Vitamin B₂ (c) Vitamin B₁₂ (d) Vitamin C

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Correct Answer: (a) Vitamin B₁

Explanation:
Thiamine (Vitamin B₁) deficiency causes beriberi

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

(a) Pentan-2-ol (b) Pentan-3-ol (c) 2-Methylbutan-1-ol (d) 3-Methylbutan-2-ol

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Correct Answer: (a) Pentan-2-ol

Explanation:
Five-carbon chain with -OH at position 2

6. The correct order of acidic strength of oxides is:

(a) Na₂O > MgO > Al₂O₃ > SiO₂ (b) SiO₂ > Al₂O₃ > MgO > Na₂O (c) Al₂O₃ > SiO₂ > MgO > Na₂O (d) Na₂O > Al₂O₃ > MgO > SiO₂

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Correct Answer: (b) SiO₂ > Al₂O₃ > MgO > Na₂O

Explanation:
Acidic character increases across the period

7. The integrated rate equation for a first order reaction is:

(a) k = (2.303/t) log([A]₀/[A]) (b) k = (1/t) ([A]₀ - [A]) (c) k = (1/2t) ([A]₀ - [A])² (d) k = (1/t) log([A]₀/[A])

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Correct Answer: (a) k = (2.303/t) log([A]₀/[A])

Explanation:
Standard first order integrated rate law (using log base 10)

8. The flux used in the extraction of iron from haematite is:

(a) Silica (b) Limestone (c) Coke (d) Calcium silicate

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Correct Answer: (b) Limestone

Explanation:
CaCO₃ decomposes to CaO which acts as flux to remove SiO₂

9. The polymer used in making optical lenses is:

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

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Correct Answer: (a) Perspex

Explanation:
Polymethyl methacrylate (PMMA) is used for lenses

10. The co-factor required by carboxylase enzymes is:

(a) Biotin (b) Thiamine (c) Niacin (d) Riboflavin

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Correct Answer: (a) Biotin

Explanation:
Biotin acts as a carrier of CO₂ in carboxylation reactions