The vapour pressure curve of the mixture of ethanol and acetone is higher than its constituents because:

Weaking of interactions between molecules takes place

The correct answer is option 1. Weaking of interactions between molecules takes place.

When two liquids are mixed together to form a solution, the interactions between molecules can change. In the case of ethanol and acetone, both molecules have similar molecular structures and can form hydrogen bonds with each other.

When ethanol and acetone are mixed, the interactions between ethanol molecules, acetone molecules, and ethanol-acetone molecules occur simultaneously. These interactions can disrupt the cohesive forces between like molecules (ethanol-ethanol and acetone-acetone) and enhance the adhesive forces between unlike molecules (ethanol-acetone).

As a result, the overall intermolecular forces in the mixture can be weaker than in the pure components, leading to a higher vapor pressure. This is because weaker intermolecular forces make it easier for molecules to escape from the liquid phase into the vapor phase, thus increasing the vapor pressure of the mixture compared to its pure components.