If $\Delta {\text{V}}_{\text{mix}}<0$ , then it shows

If $\Delta {\text{V}}_{\text{mix}}<0$ , then it shows negative deviation from Raoult’s law. The reason is the interaction forces between A and B are greater than A-A and B-B. So, during the dissolution process volume is decreased,$\Delta {\text{V}}_{\text{mix}}<0$ .