Five identical capacitors,each of capacitance $20 \mu F$,are connected to a battery of $150 V$ in the combination shown in the diagram. What is the total amount of charge stored?

Seven capacitors,each of capacity $2\,\mu F$,are to be connected to have a total capacity of $\frac{10}{11}\,\mu F$. Which of the following figures shows the correct arrangement?

Two capacitors of capacitance $C$ and $2C$ are connected in parallel and charged to a potential difference $V$. The battery is then disconnected,and the space between the plates of the capacitors is completely filled with a dielectric material of constant $K$. Determine the new potential difference across the capacitors.

$A$ 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.

$A$ circuit is connected as shown in the figure with the switch $S$ open. When the switch is closed,the total amount of charge that flows from $Y$ to $X$ is

The diagram shows four capacitors with capacitances and breakdown voltages as mentioned. What should be the maximum value of the external emf source such that no capacitor breaks down? (in $kV$)