The most suitable reagent for the following conversion is:

\(\begin{align} CH_3CH_2CH_2CH_3 \rightarrow\ & CH_3CH_2CH_2CH_2Cl\ +\ \\ & CH_3CH_2CHClCH_3\end{align} \)

1. Cl2/UV light

2. NaCl + H2SO4

3. Cl2 gas in dark

4. Cl2 gas in the presence of iron in dark

Hint: Follow free radical substitution reaction

The present reaction is a  free substitution reaction which involves the substitution of 1° and

2° hydrogen of given hydrocarbon by chlorine reagent. This reaction occurs with UV light or high thermal conditions.

This substitution reaction will not occur at room temperature conditions because homolytic fission to generate free radical substitution will not occur at this temperature condition.

The systematic mechanism will be as follows:-

So, Option (a) is correct.