Find the maximum charge on the capacitor $C$ in the following circuit in $\mu C$.

$A$ capacitor of capacitance $C$ is initially charged to a potential difference of $V$ $volt$. Now it is connected to a battery of $2V$ with opposite polarity. The ratio of heat generated to the final energy stored in the capacitor will be

Two capacitors of capacities $C_1$ and $C_2$ are charged to voltages $V_1$ and $V_2$ respectively. There will be no exchange of energy in connecting them in parallel,if

$A$ conducting sphere of radius $a$ has charge $Q$ on it. It is enclosed by a neutral conducting concentric spherical shell having inner radius $2a$ and outer radius $3a$. Find the electrostatic energy of the system.

Seven capacitors,each of capacitance $2\ \mu F$,are connected in such a way that the total equivalent capacitance is $\frac{10}{11}\ \mu F$. Which of the following circuit diagrams represents this arrangement?

In the circuit shown below, $C_1 = 10 \, \mu F$, $C_2 = C_3 = 20 \, \mu F$, and $C_4 = 40 \, \mu F$. If the charge on $C_1$ is $20 \, \mu C$, then the potential difference between $X$ and $Y$ is ......... $V$.