In the following reaction ‘X’ is  $C{H}_3{\left(C{H}_2\right)}_{4}C{H}_3\underset{HCl\Delta }{\overset{AhyAlC{l}_3}{\to }}\underset{Majorproduct}{\text{'}X\text{'}}$

n-alkanes on heating in this presence of anhydrous  and hydrogens chloride gas isomerise to branched  Chain alkanes. The major product has one methyl side chain
 $C{H}_3{\left(C{H}_2\right)}_{4}C{H}_3\underset{HCl\Delta }{\overset{AhyAlC{l}_3}{\to }}C{H}_3-\underset{\underset{C{H}_3}{|}}{C{H}_{ }}-{\left(C{H}_2\right)}_2-C{H}_3$
  2-methylpentane(major)