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:

An open-ended $U$-tube of uniform cross-sectional area contains water (density $1.0 \text{ g/cm}^3$) standing initially $20 \text{ cm}$ from the bottom in each arm. An immiscible liquid of density $4.0 \text{ g/cm}^3$ is added to one arm until a layer $5 \text{ cm}$ high forms,as shown in the figure. What is the ratio $h_2/h_1$ of the heights of the liquid in the two arms?

The pressure at the sea surface is .......... $P_{a}$.

In which layer of the atmosphere is water vapour present?

$A$ tank $5 \,m$ high is half filled with water and then is filled to the top with oil of density $0.85 \,g/cm^3$. The pressure at the bottom of the tank,due to these liquids is ........ $g/cm^2$.

Liquid is ...... while gas is ...... . (Fill in the blank) [incompressible,compressible]