Statement I: The vapours above a liquid solution of two volatile liquids is always more rich in more volatile component.

Statement II: More volatile component has lower boiling point.

If Statement I is INCORRECT, but Statement II is CORRECT.

The correct answer is: 4. If Statement I is INCORRECT, but Statement II is CORRECT.

Statement I: The vapors above a liquid solution of two volatile liquids are always more rich in the more volatile component.

This statement is incorrect. The composition of the vapor above a liquid solution of two volatile liquids will depend on the relative volatility of the components and the overall composition of the solution. It is not always the case that the vapor will be more enriched in the more volatile component. The composition of the vapor phase can vary depending on factors such as the relative amounts of the components and their relative vapor pressures.

Statement II: The more volatile component has a lower boiling point.

This statement is correct. In a binary mixture of two volatile components, the more volatile component will generally have a lower boiling point compared to the less volatile component. This is because the more volatile component has a higher tendency to evaporate and escape from the liquid phase at a lower temperature.

Since Statement I is incorrect, but Statement II is correct, the correct answer is 4. If Statement I is INCORRECT, but Statement II is CORRECT.