$A$ disc of paper of radius $R$ has a hole of radius $r$. It is floating on a liquid of surface tension $T$. The force of surface tension on the disc is

At which of the following temperatures,the value of surface tension of water is minimum in $^oC$?

Describe a simple experiment for the measurement of the surface tension of a liquid.

$A$ straw of circular cross-section of radius $R$ and negligible thickness is dipped vertically into a liquid of surface tension $T$. If the contact angle between the liquid and the straw material is $53^{\circ}$, what is the force acting on the straw due to the surface tension of the liquid? (Given: $\cos 53^{\circ} = 0.6$)

Assertion $(A)$: At critical temperature,the surface tension of liquids becomes zero.
Reason $(R)$: At critical temperature,the intermolecular forces for liquids and gases become equal.

$A$ square frame of each side $L$ is dipped in a soap solution and taken out. The force acting on the film formed is ($T$ = surface tension of soap solution). (in $TL$)