Glycerine of density $1.25 \times 10^3 \mathrm{~kg} / \mathrm{m}^3$ is flowing in conical shaped horizontal pipe. Crosssectional area of the pipe at its both ends is $10 \mathrm{~cm}^2$ and $5 \mathrm{~cm}^2$ respectively. Pressure difference at both the ends is $3 \mathrm{~N} / \mathrm{m}^2$. Rate of flow of liquid in the pipe is

Two spherical soap bubbles of radii '$$a$$' and '$$b$$' in vacuum coalesce under isothermal conditions. The resulting bubble has a radius equal to

1000 small water drops of equal size combine to form a big drop. The ratio of final surface energy to the total initial surface energy is

It is easier to spray water to which soap is added because addition of soap to water