If  $p_{\text{real }}$and $p_{\text{ideal }}$ are the pressures of a gas calculated by using van der Waals and ideal gas equations, the condition at which $p_{\text{real }}>p_{\text{ideal }}$ is 

Solution:

If  $p_{\text{real }}$and $p_{\text{ideal }}$ are the pressures of a gas calculated by using van der Waals and ideal gas equations, the condition at which $p_{\text{real }}>p_{\text{ideal }}$ is $a<\frac{RTb}{1-nb/V}$.

The amount of the attraction between gas molecules is represented by the Van der Waal constant 'a,' and the effective volume of the gas molecules is represented by the Van der Waal constant 'b.

Hence the correct option is A.