A rectangular film of liquid is extended from ( 4 cm × 2 cm ) to ( 5 cm × 4 cm ). If the work done is 3 × 10^-4 J, the value of the surface tension…

A rectangular film of liquid is extended from ($\displaystyle 4 \mathrm{~cm} \times 2 \mathrm{~cm}$) to ($\displaystyle 5 \mathrm{~cm} \times 4 \mathrm{~cm}$). If the work done is $\displaystyle 3 \times 10^{-4} \mathrm{~J}$, the value of the surface tension of the liquid is