Work W is required to form a soap bubble of soap solution of volume V. What amount of work is required to be done to form a bubble of volume 8V?

If T be the surface tension of soap solution and r be the radius of smaller bubble then,W=2×4πr2×T=8πr2TNow , 43πR3=8×43πr3⇒R=2r∴W′=2×4πR2T=4×8πr2T=4W