In a mixture of A and B, components show negative deviation when:

A – B interaction is stronger than A – A and B – B interaction

The correct answer is option 1. A – B interaction is stronger than A – A and B – B interaction.

When a mixture of components A and B is considered, the behavior of the mixture can deviate from the ideal behavior predicted by Raoult's law. Raoult's law states that the vapor pressure of a component in a mixture is directly proportional to its mole fraction in the mixture. However, in some cases, the actual vapor pressure deviates from the values predicted by Raoult's law.

Negative deviation occurs when the actual vapor pressure of a component in the mixture is lower than the vapor pressure predicted by Raoult's law. This means that the intermolecular forces between the components are stronger than the forces within pure components.

In option (1), it is stated that the A-B interaction is stronger than the A-A and B-B interactions. This means that the attraction or interaction between molecules of component A and component B is stronger than the interactions between A-A or B-B molecules.

As a result, when A and B are mixed together, the stronger A-B interaction causes the molecules of A and B to preferentially interact with each other rather than with their own kind. This stronger interaction leads to a decrease in the vapor pressure of each component in the mixture compared to what is predicted by Raoult's law.

The reduced vapor pressure occurs because the stronger A-B interaction holds the molecules of A and B more tightly in the liquid phase, making it more difficult for them to escape into the vapor phase. Consequently, the vapor pressure of each component is lower than expected, resulting in a negative deviation from Raoult's law.

In summary, option (1) is the correct choice because negative deviation occurs when the A-B interaction is stronger than the A-A and B-B interactions. This stronger interaction causes the components to preferentially interact with each other, leading to a decrease in vapor pressure and deviation from Raoult's law.