Pressure at the bottom of a tank of water is $3P$,where $P$ is atmospheric pressure. If water is drawn out till the level of water is lowered by one-fifth,then the pressure at the bottom of the tank is

Explain the hydrostatic paradox.

The density changes with pressure for which fluid? Give reason.

Which of the following quantities is expressed as force per unit area?

If two liquids of same masses but densities $\rho_1$ and $\rho_2$ respectively are mixed,then the density of the mixture is given by:

In the arrangement shown, both the vessels $A$ and $B$ are identical, but the amount of water in $B$ is double that in $A$. The vessels are closed by identical leak-proof pistons at the same height. The pistons are connected to the ends of a lever arm. There is no friction between the pistons and the container walls. The system is in equilibrium in the situation shown. Now, the valve in the horizontal tube connecting both the vessels is opened. In which direction will the water flow through the tube?