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Q.
Which one of the following gives only one monochloro derivative?
Hydrocarbons
Solution:
$neo$-Pentane or $2$, $2$-dimethylpropane has only primary hydrogen hence it can give only monochloro derivative. All other compounds have $1^{\circ}$, $2^{\circ}$ and $3^{\circ}$ hydrogens hence they give mono, di or trisubstituted products.