Two small drops of mercury each of radius $$r$$ coalesce to form a large single drop. The ratio of the total surface energies before and after the change is

A molecule of water on the surface experiences a net

Eight identical drops of water falling through air with uniform velocity of $10 \mathrm{~cm} / \mathrm{s}$ combine to form a single drop of big size, then terminal velocity of the big drop will be

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