1000 drops of water of same radius r and same charge q combine to form a big drop. How many times is the potential of the big drop relative to the potential of a small drop?

$V=\frac{1}{4\pi {\in }_0}\frac{q}{r}$ volume of bigger drop = volume of 1000 small drop i.e.,
$\frac{4}{3}\pi R^3=1000\left(\frac{4}{3}\pi r^3\right)\therefore R=10r$ also  $Q=1000q$
$\therefore$  potential of bigger drop  
$\begin{array}{l}=V=\frac{1}{4\pi {\in }_0}\frac{Q}{R}=\frac{1}{4\pi {\in }_0}-\frac{1000q}{10r}\\ \therefore V^{\text{'}}=\left(\frac{1}{4\pi {\in }_0}\frac{q}{r}\right).100i.e{V}^{\text{'}}={10}^{2}V\end{array}$