Answer:
The correct option is: Activity coefficient
Step-by-step explanation:
Ideal solution is a solution that has thermodynamic properties similar to the ideal gases. The pressure of an ideal solution obeys the Raoult's law. An ideal solution has zero enthalpy of mixing and the activity coefficient of all the components of the solution is unity.
Example: The solution of 1-butanol and 2-butanol, is nearly ideal as the two chemical compounds or molecules are chemically similar.