A hydrocarbon `(A)` was found to have vapour density `36`. If forms only a single monochloro substitution product. Suggest `(A)`.

Answer

Mol. Wt of alkane `=` Vapour density `xx2=36xx2=72`
Alkane is `C_(n)H_(2n+2)`
`therefore 12n+2n+2=72`
`therefore n=5 therefore` Alknae is `C_(5)H_(12)`
Thus alkane `C_(5)H_(12)` showing only one mono substitution product is
`CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)C-CH_(3)overset(Cl_(2))rarrCH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)C-C_(2)Cl`
(A) (2,2-`dimethylpropane)