A parallel$-$plate capacitor is constructed of two square conducting sheets $4\mathrm{.}0$ cm on a side separated by an air gap $3\mathrm{.}0$ mm thick. The capacitor is first connected to a $9\mathrm{.}00$ V battery long enough to fully charge. Show your work for each step below. $($a$)$ What is the charge on the capacitor?

$($b$)$ What is the magnitude of the electric field inside the capacitor?

$($c$)$ How much energy is stored in the capacitor?