Isobutyl chloride is
(1) $\mathrm{CII}_{3} \mathrm{CII}_{2} \mathrm{CII}_{2} \mathrm{CII}_{2} \mathrm{Cl}$
(2) $\left(\mathrm{CII}_{3}\right)_{2} \mathrm{CIICII}_{2} \mathrm{Cl}$
(3) $\mathrm{CII}_{3} \mathrm{CII}_{2} \mathrm{CIIClCII}_{3}$
(4) $\left(\mathrm{CIl}_{3}\right)_{3} \mathrm{C} \mathrm{Cl}$