The property utilized in the manufacture of lead shots is

Two glass plates of area $10^{-2} \,m^2$ have a $10 \,cm$ thick water film between them. The surface tension of water is $70 \times 10^{-3} \,N/m$. The force required to separate the two glass plates from each other is (in $\,N$)

$A$ $U$-shaped wire is dipped in a soap solution and removed. The thin soap film formed between the wire and the light slider supports a weight of $1.5 \times 10^{-2} \; N$ (which includes the small weight of the slider). The length of the slider is $30 \; cm$. What is the surface tension of the film?

The value of surface tension of a liquid at critical temperature is

On heating water,bubbles formed at the bottom of the vessel detach and rise. Assume the bubbles are spheres of radius $R$ and make a circular contact of radius $r$ with the bottom of the vessel. If $r << R$ and the surface tension of water is $T$,find the value of $r$ just before the bubbles detach. (Density of water is $\rho_{w}$)

$A$ thin flat circular disc of radius $4.5 \,cm$ is placed gently over the surface of water. If the surface tension of water is $0.07 \,N \,m^{-1}$, then the excess force required to take it away from the surface is