Two capacitors of capacities $1 \; \mu F$ and $C \;\mu F$ are connected in series and the combination is charged to a potential difference of $120 \;V$ If the charge on the combination is $80\; \mu C$, the energy stored in the capacitor of capacity C in micro- Joules is :

Question

\[\begin {array} {1 1} (1)\;1800 & \quad (2)\;1600 \\ (3)\;14400 & \quad (4)\;7200 \end {array}\]