\(\therefore \,\,{\text{P}}_{{\text{solvent}}}^{\text{0}}\,\, - \,\,{P_{solution}}\, = \,\,2.5\)
\( \Rightarrow \,\,{P_{solution}}\, = \,\,100\,\, - \,\,2.5\,\, = \,\,97.5\,\,mm\)
\(\frac{{{P_0}\, - \,\,{P_S}}}{{{P_S}}}\,\, = \,\,\frac{n}{N}\,\, = \,\,\frac{{2.5}}{{97.5}}\,\, = \,\,\frac{{W\,\, \times \,\,18}}{{90\,\, \times \,97.5}}\)
[આપેલ છે: પાણીનો મોલલ ઉન્નયન અચળાંક $K _{ b }=0.5\, \,K\, kg\, mol ^{-1}$ શુદ્ધ પાણીનું ઉત્કલન બિંદુ $\left.=100^{\circ} C \right]$
$(K_f =-1.86\,^o\, C/m)$