Surface tension is exhibited by liquids due to force of attraction...

Surface tension is exhibited by liquids due to force of attraction between molecules of the liquid. The surface tension decreases with an increase in temperature and vanishes at boiling point. Given that the latent heat of vaporisation for water (L_v) = 540 k cal kg^–1, the mechanical equivalent of heat (J) = 4.2 J cal^–1, density of water (ρ_w) = 103 kg l^–1, Avogadro’s Number (N_A) = 6.0 × 10²⁶k mole^–1, and the molecular weight of water (M_A) = 18 kg for 1 k mole.During vaporisation a molecule overcomes a force F, assumed constant, to go from an inter-molecular distance d to d′. Estimate the value of F.