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

1. The number of moles in 2.8 g of CO is:

(a) 0.1 mole (b) 0.2 mole (c) 1 mole (d) 0.05 mole

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Correct Answer: (a) 0.1 mole

Explanation:
Molar mass CO = 28 g/mol → 2.8 g = 0.1 mole

2. The oxidation state of chromium in CrO₅ is:

(a) +6 (b) +5 (c) +3 (d) +10

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Correct Answer: (a) +6

Explanation:
CrO₅ has peroxide linkages → Cr = +6

3. The pH of 0.05 M Ba(OH)₂ solution is:

(a) 12.7 (b) 13 (c) 11 (d) 10

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Correct Answer: (a) 12.7

Explanation:
[OH⁻] = 0.1 M → pOH = 1 → pH = 13 (approximate)

4. The hybridisation of carbon in graphite is:

(a) sp (b) sp² (c) sp³ (d) sp³d

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Correct Answer: (b) sp²

Explanation:
Layered structure with trigonal planar geometry

5. The IUPAC name of CH₃CH₂CH₂CHO is:

(a) Propanal (b) Butanal (c) Pentanal (d) Butanone

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Correct Answer: (b) Butanal

Explanation:
Four-carbon aldehyde

6. The number of sigma and pi bonds in CH₃-C≡C-CH₃ is:

(a) 9 sigma, 2 pi (b) 8 sigma, 2 pi (c) 10 sigma, 1 pi (d) 7 sigma, 3 pi

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Correct Answer: (a) 9 sigma, 2 pi

Explanation:
2,2-Butyne has 9 σ and 2 π bonds

7. The molarity of 5.6 g KOH in 200 mL solution is:

(a) 0.5 M (b) 0.25 M (c) 1 M (d) 0.1 M

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Correct Answer: (a) 0.5 M

Explanation:
Moles = 5.6 / 56 = 0.1, Volume = 0.2 L → M = 0.5

8. The element with electronic configuration [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p² is:

(a) Lead (b) Mercury (c) Thallium (d) Bismuth

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Correct Answer: (a) Lead

Explanation:
Atomic number 82 → Lead

9. The functional group in acid anhydrides is:

(a) -CO-O-CO- (b) -COOH (c) -COO- (d) -CONH₂

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Correct Answer: (a) -CO-O-CO-

Explanation:
Anhydride functional group is -CO-O-CO-

10. The shape of XeOF₄ molecule is:

(a) Square pyramidal (b) Octahedral (c) Trigonal bipyramidal (d) T-shaped

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Correct Answer: (a) Square pyramidal

Explanation:
5 bond pairs + 1 lone pair