Electric potential & current

Figure 3 shows a circuit with four resistors, A, B, C, D, a battery, a capacitor and a switch. The capacitor consists of two square metal plates, each with an area of 2.0m^2. The plates are parallel to each other and are aeparated by a gap of 3.0mm. The spce between the gap contains air.

a) Find the effective resistance for the shown combination of resistors A, B and C.

b) What is the capacitance of the parallel plate arrangement?

c) What is the voltage drop across the capacitor in the steady state?

d) Sketch a graph to show how the potential difference across the capacitor varies with time after the switch is opened

Link of Figure 3
http://s582.photobucket.com/albums/ss266/fn14829/?action=view&current=0002.jpg