For the circuit shown,which of the following statements is true?

Initially, $n$ identical capacitors are joined in parallel, and are charged to potential $V$. Now they are separated and joined in series. Then:

Each capacitor shown in the figure has a capacitance of $5.0 \ \mu F$. The battery has an $emf$ of $50 \ V$. If the switch $S$ is closed,what amount of charge will flow through $AB$?

Two conducting shells of radius $a$ and $b$ are connected by a conducting wire as shown in the figure. The larger shell is grounded. The capacitance of the system is:

The space between the plates of a parallel plate capacitor of plate area $4 \ cm^2$ and separation $d = 1.77 \ mm$ is filled with uniform dielectric materials with dielectric constants $k_1 = 5$ and $k_2 = 3$ as shown in the figure. Another capacitor of capacitance $7.5 \ pF$ is connected in parallel with it. The effective capacitance of this combination is . . . . . . $pF$. (Given $\varepsilon_0 = 8.85 \times 10^{-12} \ F/m$)

The following figure shows a $9 \ V$ battery and $3$ uncharged capacitors of capacitances $C_1 = C_2 = C_3 = 1 \ \mu F$. The switch is thrown to the right side until capacitor $C_1$ is fully charged,then the switch is thrown to the left. The final charge on capacitor $C_2$ is (in $\mu C$)