A parallel-plate capacitor with plates of area 25.0 cm² and 2.00 mm separation is charged to a potential difference of 250 V and disconnected from the source. The capacitor is then immersed in distilled water. Assuming the liquid is an insulator, determine (a) the capacitance before and after immersion, (b) the potential difference after immersion, and (c) the change in energy of the capacitor.