A parallel-plate air-filled capacitor having area 35 cm^2 and plate spacing 1.4 mm is charged to a potential difference of 770 V. Find (a) the capacitance in picofarads, (b) the magnitude of the charge in nanocoulombs on each plate, (c) the stored energy in microjoules, (d) the electric field in N/C between the plates, (e) the energy density between the plates.