Statement I: Addition of a non-volatile solute to a volatile solvent increases the boiling point.

Statement II: Addition of non-volatile solute to a volatile solvent results decrease in the vapour pressure.

If both statements are CORRECT, and Statement II is the CORRECT explanation of Statement I.

The correct answer is option 1. If both statements are CORRECT, and Statement II is the CORRECT explanation of Statement I.

Statement I: Addition of a non-volatile solute to a volatile solvent increases the boiling point.

This statement is correct. The addition of a non-volatile solute to a volatile solvent does indeed increase the boiling point of the solvent. The presence of the solute disrupts the vaporization process by reducing the vapor pressure of the solvent. Consequently, a higher temperature is required to achieve the vapor pressure equal to the atmospheric pressure, resulting in an elevated boiling point.

Statement II: Addition of non-volatile solute to a volatile solvent results in a decrease in the vapor pressure.

This statement is also correct. The addition of a non-volatile solute to a volatile solvent leads to a decrease in the vapor pressure of the solvent. The solute particles occupy some of the solvent's surface area, limiting the number of solvent molecules available to escape into the vapor phase. As a result, the vapor pressure decreases compared to the pure solvent.

Statement II provides the correct explanation for Statement I because the decrease in vapor pressure caused by the presence of the non-volatile solute directly contributes to the increase in boiling point. Therefore, the correct answer is: If both statements are CORRECT, and Statement II is the CORRECT explanation of Statement I.