$A$ soap bubble is given a negative charge,then its radius

$A$ series combination of $n_1$ capacitors,each of value $C_1$,is charged by a source of potential difference $4V$. When another parallel combination of $n_2$ capacitors,each of value $C_2$,is charged by a source of potential difference $V$,it has the same total energy stored in it as the first combination has. The value of $C_2$ in terms of $C_1$ is:

When two identical capacitors are charged individually to different potentials and connected in parallel to each other,after disconnecting them from the source:

The potential difference between the points $P$ and $Q$ in the adjoining circuit will be :-

The ratio of potential difference that must be applied across parallel and series combination of two capacitors $C_1$ and $C_2$ with their capacitance in the ratio $1: 2$ so that energy stored in these two cases becomes same is

In the circuit shown,$q_2$ and $q_3$ are respectively (Initially all capacitors are uncharged).