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Chemistry MCQ Practice 13 — Science Foundation Course for Class 11 & 12
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1.
The number of moles in 27 g of Al (atomic mass 27) is:
(a) 1 mole
(b) 0.5 mole
(c) 2 moles
(d) 0.1 mole
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Correct Answer: (a) 1 mole
Explanation:
Moles = 27 / 27 = 1 mole
2.
The oxidation state of Mn in MnO₄⁻ is:
(a) +5
(b) +6
(c) +7
(d) +4
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Correct Answer: (c) +7
Explanation:
x + 4(-2) = -1 → x = +7
3.
The pH of 0.05 M HCl solution is:
(a) 1.3
(b) 2
(c) 3
(d) 4
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Correct Answer: (a) 1.3
Explanation:
[H⁺] = 0.05 M → pH = -log(0.05) ≈ 1.3
4.
The hybridisation of carbon in benzene is:
(a) sp
(b) sp²
(c) sp³
(d) sp³d
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Correct Answer: (b) sp²
Explanation:
Trigonal planar geometry with delocalized electrons
5.
The IUPAC name of CH₃CH₂CH₂COCH₃ is:
(a) Pentan-2-one
(b) Pentan-3-one
(c) Butanone
(d) Hexanone
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Correct Answer: (a) Pentan-2-one
Explanation:
Five-carbon ketone with carbonyl at position 2
6.
The number of sigma and pi bonds in CH₃-CH=CH-CH₃ is:
(a) 11 sigma, 1 pi
(b) 10 sigma, 1 pi
(c) 12 sigma, 0 pi
(d) 9 sigma, 2 pi
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Correct Answer: (a) 11 sigma, 1 pi
Explanation:
2-Butene has 11 σ and 1 π bond
7.
The molarity of 5.6 g KOH in 100 mL solution is:
(a) 1 M
(b) 0.5 M
(c) 2 M
(d) 0.1 M
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Correct Answer: (a) 1 M
Explanation:
Moles = 5.6 / 56 = 0.1, Volume = 0.1 L → M = 1
8.
The element with electronic configuration [Kr] 5s² 4d¹⁰ 5p³ is:
(a) Antimony
(b) Arsenic
(c) Indium
(d) Tellurium
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Correct Answer: (a) Antimony
Explanation:
Atomic number 51 → Antimony
9.
The functional group in cyanides is:
(a) -CN
(b) -NC
(c) -NO₂
(d) -NH₂
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Correct Answer: (a) -CN
Explanation:
Cyano group (-C≡N)
10.
The shape of ClF₅ molecule is:
(a) Trigonal bipyramidal
(b) Square pyramidal
(c) Octahedral
(d) T-shaped
Show Answer & Explanation
Correct Answer: (b) Square pyramidal
Explanation:
5 bond pairs + 1 lone pair