Water rises up to a height of $4 \,cm$ in a capillary tube. The lower end of the capillary tube is at a depth of $8 \,cm$ below the water level. The mouth pressure required to blow an air bubble at the lower end of the capillary will be '$X$' $cm$ of water,where $X$ is equal to

$A$ glass capillary tube of inner diameter $0.28 \,mm$ is lowered vertically into water in a vessel. The pressure to be applied on the water in the capillary tube so that the water level in the tube is the same as that in the vessel is ............ $\times 10^3 \,N/m^2$ (surface tension of water $= 0.07 \,N/m$ and atmospheric pressure $= 10^5 \,N/m^2$).

The correct curve between the height or depression $h$ of liquid in a capillary tube and its radius $r$ is

$A$ glass rod of radius $r_1$ is inserted symmetrically into a vertical capillary tube of radius $r_2$ $(r_1 < r_2)$ such that their lower ends are at the same level. The arrangement is dipped in water. The height to which water will rise into the tube will be ($\rho =$ density of water,$T =$ surface tension of water,$g =$ acceleration due to gravity).

Why is moisture retained in the soil when a farm is ploughed?

If the surface tension of water is $0.06 \, N/m$,then the capillary rise in a tube of diameter $1 \, mm$ is ....... $cm$ (assume $\theta = 0^\circ$,$g = 10 \, m/s^2$,and density of water $\rho = 1000 \, kg/m^3$).