The surface tension of two liquids are respectively $30$ and $60 \mathrm{dyne} {\mathrm{cm}}^{-1}$. The liquids drop from the ends of two tubes of the same radius. The ratio of the weights of the two drops is

When kerosene is poured on the surface of water, the larvae and mosquitoes do not remain alive because

A glass plate is partly dipped vertically in the mercury and the angle of contact is measured. If the plate is inclined, then the angle of contact will