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

$A$ beaker of radius $15\, cm$ is filled with a liquid of surface tension $0.075\, N/m$. The force across an imaginary diameter on the surface of the liquid is:

At critical temperature,the surface tension of a liquid is

Why does the free surface of a liquid tend to contract?

$A$ wire of length $10 \text{ cm}$ is gently placed horizontally on the surface of water having surface tension of $75 \times 10^{-3} \text{ N/m}$. What force is required to just pull up the wire from the water surface?

There is a horizontal film of soap solution. On it,a thread is placed in the form of a loop. The film is pierced inside the loop,and the thread becomes a circular loop of radius $R$. If the surface tension of the soap solution is $T$,what will be the tension in the thread?