In which layer of the atmosphere is water vapour present?

$A$ closed rectangular tank is completely filled with water and is accelerated horizontally with an acceleration $a$ towards the right. Pressure is $(i)$ maximum at,and $(ii)$ minimum at:

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

Three identical vessels are filled to the same height with three different liquids $A, B$ and $C$ $(\rho_A > \rho_B > \rho_C)$. The pressure at the base will be

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

The densities of ice and water are $\rho$ and $\sigma$ respectively. What is the change in volume when a mass $M$ of ice melts?