A gaseous hydrocarbon (12ml) is exploded with excess of oxygen. On cooling, the contraction in volume is 48ml and there is further contraction of 48ml in volume when passed through lime water. The molecular formula of hydrocarbon is
(1) $C_3H_6$
(2) $C_3H_8$
(3) $C_4H_{10}$
(4) $C_4H_8$
