Compound $A$ on reaction with chlorine in the presence of $U.V.$ light gives $B$; which when reacted with $NaNO_{2}$ in the solvent $N, N$-dimethylformamide $(DMF)$,gives $2$-nitrobutane. The compound $A$ is:

Identify the correct statements from the following:
$(i)$ Petrol and $CNG$ operated automobiles cause less pollution.
$(ii)$ Alkanes having tertiary hydrogen can be oxidised to alcohols by $KMnO_4$.
$(iii)$ Methane can be prepared by Kolbe's electrolytic method.
$(iv)$ Alkyl chloride on reduction with zinc and dilute hydrochloric acid gives alkane.

$n$-Butane on monochlorination under photochemical conditions gives an optically active compound "$P$". "$P$" on further chlorination gives dichloro compounds. The number of dichloro compounds obtained (ignore stereoisomers) is:

$CH_3-CH_2-CH_2-CH_2-CH_3 \xrightarrow{CH_2N_2/\Delta} \text{Product}$.
Which of the following product$(s)$ can be obtained in the above reaction?

What is an alkane substitution reaction? Give the names and possibilities of different types of substitution reactions.

The catalyst used for the isomerisation of $n$-alkanes to branched chain alkanes is