27. The work done in increasing the size of a soap film from

10 cm× 6 cm to 10 cm × 11 cm is 3 ×10-4 joule. The surface tension of the film is   (a) 1.5 x 10-2N/m (b) 3.0 x 10-2N/m (c)  6.0 x  10-2N/m (d)  11 x 10-2N/m Ans. b …