$2.$The presence of $\_\_\_\_\_\_\_\_\_$ in a solution can significantly affect the measurement and interpretation of activity coefficients.

A critical step in designing separation processes is the accurate prediction of $\_\_\_\_\_\_\_\_\_$ coefficients under varying conditions.

The $\_\_\_\_\_\_\_\_\_$ equation provides a basis for understanding the non$-$ideal mixing behavior in solutions and predicting phase equilibria.

High$-$pressure phase equilibria studies often require the adjustment of fugacity coefficients to account for $\_\_\_\_\_\_\_\_\_$ deviations.