c
જો \(\,{\text{P}}_{{\text{Solvent}}}^0\, = \,\,100\,mm\) આથી, બા.દ. માં  ધટડો  \(= {\text{2}}{\text{.5}}\,\,{\text{mm}}\)

\(\therefore \,\,{\text{P}}_{{\text{solvent}}}^{\text{0}}\,\, - \,\,{P_{solution}}\, = \,\,2.5\)

\( \Rightarrow \,\,{P_{solution}}\, = \,\,100\,\, - \,\,2.5\,\, = \,\,97.5\,\,mm\)

\(\frac{{{P_0}\, - \,\,{P_S}}}{{{P_S}}}\,\, = \,\,\frac{n}{N}\,\, = \,\,\frac{{2.5}}{{97.5}}\,\, = \,\,\frac{{W\,\, \times \,\,18}}{{90\,\, \times \,97.5}}\)