Two charged spheres of radii $10\, cm$ and $15\, cm$ are connected by a thin wire. No current will flow, if they have

Two thin concentric hollow conducting spheres of radii $R_1$ and $R_2$ bear charges $Q_1$ and $Q_2$ respectively. If $R_1 < R_2$, then the potential of a point at a distance $r$ from the centre $(R_1 < r < R_2)$ is

Is electrostatic potential vector or scalar ?

A neutral spherical copper particle has a radius of $10 \,nm \left(1 \,nm =10^{-9} \,m \right)$. It gets charged by applying the voltage slowly adding one electron at a time. Then, the graph of the total charge on the particle versus the applied voltage would look like

$64$ drops of mercury each charged to a potential of $10\,V$. They are combined to form one bigger drop. The potential of this drop will be.......$V$ (Assume all the drops to be spherical)

Two hollow conducting spheres of radii $R_{1}$ and $R_{2}$ $\left(R_{1}>>R_{2}\right)$ have equal charges. The potential would be: