$3.$ How do deviations from Raoult's Law illustrate the importance of activity coefficients in solution thermodynamics?

$-$ What is the significance of the Lewis$-$Randall rule in the context of fugacity and activity coefficients?

$-$ Explain how binary interaction parameters influence the calculation of activity coefficients in models like NRTL and Wilson.

$-$ Describe the use of excess properties in understanding the non$-$ideality of solutions.