For a 2-port network to be reciprocal

For the series R-L-C circuit of figure(a), the partial phasor diagram at a certain frequency is shown in figure (b).The operating frequency of the circuit is:

Relative to a given fixed tree of a network

For the circuit shown below different time constants are given :

1. 1. $0.5 \times 10^{-3} \mathrm{sec}$

2. 2. $2 \times 10^{-3} \mathrm{sec}$

3. 3. $0.25 \times 10^{-3} \mathrm{sec}$

4. 4. $10^{-3} \mathrm{sec}$

What are the charging and discharging times respectively :