Explanation
a) Surface tension is defined as a force per unit length perpendicular to any line on the surface of the liquid OR Property of a liquid which makes the surface of liquid behave like an elastic skin.
(b) Surface tension = F/21
=7.3 x 1\(^{-2}\) x 2 x 0.04 = 5.8 x 10\(^{-3}\)N

