The radius of one soap bubble is four times that of another. What is the ratio of the excess pressure inside the two bubbles?

The radii of two mercury drops are $R_1$ and $R_2$. Under isothermal conditions,a single drop of radius $R$ is formed from them. The relation between $R, R_1$ and $R_2$ is

If the radius of a soap bubble is four times that of another,then the ratio of their excess pressures will be

$27$ drops of mercury coalesce to form a bigger drop. What is the relative increase in surface energy?

When a large bubble rises from the bottom of a lake to the surface,its radius doubles. If atmospheric pressure is equal to that of a column of water of height $H$,then the depth of the lake is:

$1000$ spherical drops of water each $10^{-8} \ m$ in diameter coalesce to form one large spherical drop. The amount of energy liberated in this process (in joule) is (surface tension of water is $0.075 \ N/m$).