On mixing an alkane with chlorine and irradiating with ultra-violet light, it forms only one mono-chloro-alkane. The alkane is

Hydrocarbon $(A)$ reacts with bromine by substitution to form an alkyl bromide,which by Wurtz reaction is converted to a gaseous hydrocarbon containing less than four carbon atoms. $(A)$ is

Ethyl iodide and $n$-propyl iodide are allowed to undergo Wurtz reaction. The alkane which will not be obtained in this reaction is

Methane reacts with steam at $1273 \ K$ in the presence of a nickel catalyst to form:

The chemicals and the reaction conditions required for the preparation of ethane are:

The compound $(X)$ on $(i)$ heating in the presence of anhydrous $AlCl_3$ and $HCl$ gas gives $2,4$-dimethylpentane, $(ii)$ aromatization gives toluene, and $(iii)$ cyclisation gives methylcyclohexane. The correct name of compound $(X)$ is: