Which of the following is a possible application of an $RC$ circuit?

As shown in the figure,if a capacitor $C$ is charged by connecting it with a battery of voltage $V$ through a resistance $R$,then the energy supplied by the battery will be:

As shown in the figure,in steady state,the charge stored in the capacitor is $....... \times 10^{-6} \, C$.

Find the charge on the capacitor $1 \text{ s}$ after opening the switch,given that the switch was closed for a long time $(t = \infty)$.

At steady state,the charge on the capacitor,as shown in the circuit below,is . . . . . . $\mu \text{C}.$

After closing the key in the given circuit:
$(a)$ Bulb $(2)$ will glow and maintain its brightness.
$(b)$ Brightness of bulb $(1)$ will gradually decrease and at steady state it goes completely dark.