Answer:
new energy of the capacitor is half that of initial energy
Step-by-step explanation:
As we know that the energy stored in the capacitor is given as

here we know that capacitance of parallel plate capacitor is given as

V = voltage of battery
so now we have capacitor remains connected to the same battery and the separation between the plates is doubled
so we have

so now the energy stored between the plates is

so new energy of the capacitor is half