A parallel-plate capacitor in air has a plate separation of 1.50 cm and area of 25.0 cm^2. The plates are charged to a potential difference of 250 V and disconnected from the source. The capacitor is then immersed in distilled water. Determine:
(a) the charge on the plates before and after immersion,
(b) the capacitance and potential difference after immersion, and
(c) the change in the amount of energy stored in the capacitor.