Please show necessary mathematical calculations with explanation where needed and answer this.

2.

(i) A capacitor is discharging through a resistor. If it takes a time T for the charge on a capacitor to drop to half its initial value, how long (in terms of T) does it take for the stored energy to drop to half its initial value?

(ii) For the circuit shown in the Figure below,

C = 0.120 ?F and ? = 100 V. The switch throw is rotated to contact b after having been at contact a for a long time, and 4.00 s later the potential difference across the capacitor is equal to ?/2. What is the value of R?