$A$ barometer tube,containing mercury,is lowered in a vessel containing mercury until only $50 \, cm$ of the tube is above the level of mercury in the vessel. If the atmospheric pressure is $75 \, cm$ of mercury,what is the pressure at the top of the tube?

The pressure at half the depth of a lake is $2/3$ of the pressure at its bottom. What is the depth of the lake in $m$?

$A$ barometer is kept in an elevator accelerating upwards with an acceleration $a$. Find the most likely pressure inside the elevator.

The gauge pressure at a depth of $50 \,m$ in a sea is (Density of sea water is $1025 \,kg \,m^{-3}$ and $g=10 \,ms^{-2}$ ). (in $\,Pa$)

What are the difficulties arising from using water in a barometer instead of mercury?

$A$ submarine experiences a pressure of $5.05 \times 10^6 \, Pa$ at a depth of $d_1$ in a sea. When it goes further to a depth of $d_2,$ it experiences a pressure of $8.08 \times 10^6 \, Pa.$ Then $d_2 - d_1$ is approximately ........ $m$ (density of water $= 10^3 \, kg/m^3$ and acceleration due to gravity $= 10 \, m/s^2$).