Compute all parts of given problem:
Problem: A parallel-plate capacitor with plate area 2.0cm2 and air-gap separation 0.50mm is connected to a 12-V battery, and fully charged. The battery is then disconnected.
Part A: What is the charge on the capacitor?
Part B: The plates are now pulled to a separation of 0.75 mm. What is the charge on the capacitor now?
Part C: What is the potential difference between the plates now?
Part D: How much work was required to pull the plates to their new separation?
Express your knowledge to solve the above problem.