The given graph / data I, II, III and IV represent general trends observed for different physisorption and chemisorption processes under mild conditions of temperature and pressure. Which of the following choice (s) about I, II, III and IV is (are) correct?

(i) (ii)   (iii)  

The qualitative sketches I, II and III given below show the variation of surface tension with mołar concentration of three different aqueous solution of $\mathrm{KCl}, {\mathrm{CH}}_3\mathrm{OH}$ and ${\mathrm{CH}}_3\left({\mathrm{CH}}_2\right)+1, {\mathrm{OSO}}_3-{\mathrm{Na}}^{+}$ at room temperature. The correct assignment of the sketches is:

In Langmuir's model of adsorption of a gas on a solid surface,

According to Freundlich adsorption isotherm, which of the following is correct?