Solubility of a solute in a solvent $\left(\mathrm{say} {\mathrm{H}}_2\mathrm{O}\right)$is dependent on temperature as given by $\mathrm{S}={\mathrm{Ae}}^{-∆\mathrm{H}/\mathrm{RT}}$ where$∆\mathrm{H}$is heat of reaction $\mathrm{solute} +{\mathrm{H}}_2\mathrm{O}\rightleftharpoons \mathrm{solutions} ∆\mathrm{H}=\pm \mathrm{x}$ for given solution variation of log S with temperature is shown graphically. Hence, solute is: