If a section of a soap bubble of radius $r$ by a plane through its centre is considered,the force on the half due to surface tension is

An air bubble rises from the bottom to the top of a water tank in which the temperature of the water is uniform. The surface area of the bubble at the top of the tank is $125 \%$ more than its surface area at the bottom of the tank. If the atmospheric pressure is equal to the pressure of $10 \ m$ water column, then the depth of water in the tank is (in $m$)

The work done in splitting a water drop of radius $R$ into $64$ droplets is ($T=$ surface tension of water). (in $\pi TR^2$)

The excess pressure inside a spherical drop of water is three times that of another drop of water. The ratio of their surface area is

When a mercury drop of radius $R$ breaks into $n$ droplets of equal size,the radius $r$ of each droplet is

What is the ratio of the number of moles of air in two soap bubbles of radii $R_1$ and $R_2$?