JEE Main 2026 Apr 2 Shift 1, Chemistry Q22: Properties of Alkanes

JEE Main2026Apr 2, Shift 1Chemistry

Consider the isomers of hydrocarbon with molecular formula $C_{5} H_{10}$ . These isomers do not decolourise $K M n O_{4}$ solution. These isomers are subjected to chlorination with chlorine in presence of light to give monochloro compounds. The total number of monochloro compounds (structural isomers only) formed is _____.

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Solution

$C_{5} H_{10}$ with degree of unsaturation 1 that does not decolourise $K M n O_{4}$ must be a cycloalkane (no $C = C$ ). The five cyclic isomers are: cyclopentane, methylcyclobutane, ethylcyclopropane, 1,1-dimethylcyclopropane and 1,2-dimethylcyclopropane.

Counting distinct monochloro products (one per chemically distinct C–H environment) for each:

Cycloalkane	Distinct monochlorides
Cyclopentane (all H equivalent)	$1$
Methylcyclobutane	$4$
Ethylcyclopropane	$4$
1,1-Dimethylcyclopropane	$2$
1,2-Dimethylcyclopropane	$3$

Total $= 1 + 4 + 4 + 2 + 3 = 14$ .

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JEE Main 2026 Apr 2 Shift 1, Chemistry Q22: Properties of Alkanes

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