21.In a vessel of water a hole is made at a depth of 3.5 m from the free surface. The velocity of efflux will be:

22.The weight of wooden block of size 8 cm x 8 cm is 307.2 g. When it is floating in water the height of the wooden block above water level is:

23.Between layers of liquid in relative motion viscosity introduces:

24.A water tank on the top of a tall building feeds water in the taps on different floors. The water will gush out at highest speed from a tap on floor:

25.A piece of solid weighs 120g in air, 80 g in water and 60 g in a liquid, then the relative density of the solid and that of liquid are respectively: