The vapour pressure of a saturated solution of sparingly soluble salt ($\text{XCl}_3$) was $17.20\,\text{mm Hg}$ at $300\,\text{K}$. If the vapour pressure of pure $\text{H}_2\text{O}$ is $17.25\,\text{mm Hg}$ at $300\,\text{K}$, what is the solubility of sparingly soluble $\text{XCl}_3$ (in mole/Litre)?