Question

A hydrocarbon having molecular weight 70 gives a single monochloride on chlorination. How many dichlorides will be formed (including stereoisomers) on photodichlorination of the hydrocarbon?

Answer 1

Molecular formula of the hydrocarbon for the given mass would be $C_5{H}_{10}$
Double bond equivalent of $C_5{H}_{10}$ is 1.
So the possible isomers of the compound may be:



Among the isomers, only cyclopentane can give single monochloride on chlorination.
Hence upon photodichlorination of the cyclopentate, total seven dichlorides can be formed.