Compound (X) undergoes isomerization on heating with anhydrous AlCl3 and HCl gas to give branched-chain alkanes. The formation of 2,4-dimethylpentane (a 7-carbon branched alkane) indicates that (X) is a 7-carbon straight-chain alkane.
Aromatization of n-heptane at high temperature and pressure in the presence of oxides of V, Mo, or Cr supported over alumina gives toluene.
Cyclisation of n-heptane under similar conditions initially yields methylcyclohexane, which can further undergo dehydrogenation to form toluene.
Since all these reactions are characteristic of n-heptane, compound (X) is heptane.
Answer: Heptane