Solution:

A gas is close to ideal gas behavior at low pressure and high temperatures since at these conditions the gas satisfies the required conditions to be an ideal gas like the attractive forces between the molecules of gas becomes zero.

Solution:

The fugacity is also called as effective pressure in case of real gas ,and for ideal gas it numerically becomes equal to pressure so, for an gas to behave ideally we know the required conditions should be high temperature and low pressure and an standard state is usually selected where we know the value of fugacity so, it may or may not be equal to pressure.

Solution:

Both van-laar and margules equations are models to find out the activity co-efficient.

Solution:

The heat of formation is defined as amount of heat absorbed or evolved when I mol of a compound is formed from its elements in their standard states.

Solution:

Since entropy change of mixing is $${\left( {\Delta s} \right)_{mix}} = - nR\sum {} {x_i}\ln {x_i}$$
So, it is dependent on both number of moles and composition as we can see physically also that more and more number of moles we add to the system the system behavior changes and the properties changes.

Solution:

The acentric factor can’t always be greater than 1. For many monoatomic fluids the acentric factor is close to zero.

Solution:

A gas is close to ideal gas behavior at low pressure and high temperatures since at these conditions the gas satisfies the required conditions to be an ideal gas like the attractive forces between the molecules of gas becomes zero etc.