In the presence of AlCl3/HCl n-butane isomerizes to:
Cyclobutane
2-Butene
Isobutane
1-Butene
The remaining compounds are unsaturated and are not formed.
The hydrocarbon 2-methyl butane is an isomer of : (a) n-pentane (b) n-butane (c) propane (d) iso-butane