The potential of a large liquid drop when eight liquid drops are combined is $20 \mathrm{V}$. Then, the potential of each single drop was,

Two parallel plate capacitors of capacitances $C$ and $2C$ are connected in parallel and charged to a potential difference $V.$ The battery is then disconnected and the region between the plates of the capacitor $C$ is completely filled with a material of dielectric constant $K\mathit{.}$ The potential difference across the capacitors now becomes -

Find equivalent capacitance between $X$ and $Y$ if each capacitor is $4 \mathrm{\mu F}$.