CH4
CH2=CH2
CH3−CH3
CH≡CH
Hydrocarbon (A) is methane (CH4). It reacts with bromine by substitution to form methyl bromide
CH4+Br2→CH3−Br+HBr
Methyl bromide by Wurtz reaction is converted to a gaseous hydrocarbon containing less than four carbon atoms.
2CH3Br+2Na→CH3−CH3+2NaBr
In Wurtz reaction, when the same alkyl halide is used, the product alkane has an even number of C atoms.