A drop of some liquid of volume `0.04 cm^(3)` is placed on the surface of a glass slide. Then, another glass forms a thin layer of area `20 cm^(2)` between the surfaces of the two slides. To separate the slides a force of `16 xx 10^(5)` dyne has to be applied normal to the surfaces. The surface tension of the liquid is (in dyne `cm^(-1))`