Chemistry MCQ Practice 26 — Science Foundation Course for Class 11 & 12

1. The osmotic pressure of a solution containing 5 g of glucose (molar mass 180) in 200 mL at 27°C is (R = 0.0821 L atm K⁻¹ mol⁻¹):

(a) 3.41 atm (b) 6.82 atm (c) 1.70 atm (d) 13.64 atm

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Correct Answer: (a) 3.41 atm

Explanation:
π = (nRT)/V = (5/180 × 0.0821 × 300) / 0.2 ≈ 3.41 atm

2. The crystal field stabilisation energy (CFSE) for [Ti(H₂O)₆]³⁺ is:

(a) 0.4 Δ₀ (b) 0.6 Δ₀ (c) 1.2 Δ₀ (d) 0.8 Δ₀

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Correct Answer: (a) 0.4 Δ₀

Explanation:
Ti³⁺ is d¹ → CFSE = –0.4 Δ₀

3. Which of the following is a copolymer?

(a) Polythene (b) Nylon-6,6 (c) Buna-S (d) Teflon

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Correct Answer: (c) Buna-S

Explanation:
Copolymer of butadiene and styrene

4. The vitamin whose deficiency causes pellagra is:

(a) Vitamin B₁ (b) Vitamin B₂ (c) Vitamin B₃ (Niacin) (d) Vitamin B₁₂

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Correct Answer: (c) Vitamin B₃ (Niacin)

Explanation:
Niacin deficiency causes pellagra (3 Ds: dermatitis, diarrhoea, dementia)

5. The IUPAC name of the compound (CH₃)₂C=CH-CH₂-CH₃ is:

(a) 2-Methylpent-2-ene (b) 4-Methylpent-2-ene (c) 2-Methylpent-1-ene (d) 4-Methylpent-1-ene

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Correct Answer: (a) 2-Methylpent-2-ene

Explanation:
Longest chain with lowest number to double bond

6. The correct order of bond angles is:

(a) NH₃ > H₂O > BF₃ > CH₄ (b) BF₃ > CH₄ > NH₃ > H₂O (c) H₂O > NH₃ > CH₄ > BF₃ (d) CH₄ > NH₃ > H₂O > BF₃

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Correct Answer: (b) BF₃ > CH₄ > NH₃ > H₂O

Explanation:
Lone pairs cause greater repulsion → smaller bond angle

7. The time required for 90% completion of a first order reaction is:

(a) 2.303 / k (b) 2.303 log 10 / k (c) 0.693 / k (d) 2.303 log 100 / k

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Correct Answer: (b) 2.303 log 10 / k

Explanation:
t = (2.303/k) log(100/10) = (2.303/k) log 10

8. The ore of iron that is concentrated by magnetic separation is:

(a) Bauxite (b) Haematite (c) Magnetite (d) Copper pyrites

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Correct Answer: (c) Magnetite

Explanation:
Magnetite (Fe₃O₄) is magnetic and can be separated

9. The polymer used in making water pipes is:

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

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Correct Answer: (a) PVC

Explanation:
Polyvinyl chloride is commonly used for pipes

10. The enzyme that converts maltose to glucose is:

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

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Correct Answer: (a) Maltase

Explanation:
Maltase hydrolyses maltose into two glucose molecules