Explain in why on addition of 1 moe of NaCl to 1L of water, the boiling point of water increases, while addition of 1 mole of methyl alcohol to 1 L of water decreases its boilbing point .

Explanation

NaCl is non-volatile solute. So, its addition to water lowers the vapour pressure of the water. Hence, boilling poitn of water ( solution) increases. W hares methyl alcohol is more valatile than water.
So, its addition to water increases the total vapour pressure over the solution. It re sults in the decre ase of boiling point.