Reporting surface tension value

Consider the graph below reporting surface tension values versus concentration of addedsurfactant RCI, where R is a long alkyl chain with a positively charged head group, in an aqueoussolution at 25″ C. The two data seta are collected with different amounts of dissolved salt (pure waterand excess KCI). (2 marks)(a) Using the data below, estimate the minimum surface area per surfactant molecule adsorbed atthe air/water interface at 5*10 M surfactant’s concentration in pure water.(b) Is the surface area per molecule in salt solution higher or lower than that in pure water? Brieflyexplain the physico-chemical reason for your answer.8070Surface Tension, mN/m60Water50KCI Brine6401x10″1×10’1×10″1x101x10’2RCI (M)