What is the signification of 'a' in the van der Waal's equation ?

In the van der Waals equation

van der Waal's equation is true for

A gas described by van der Waals equation

A gas described by van der Waals equation

What do the constants a and b signify in van der Waals' equation ?

Using van der Waals equation (P+(a)/(V^(2)))(V-b)=RT , answer the following questions: The term that accounts for effective volume in the van der Waals equation for non-ideal gas is

Discuss in brief the significance of the van der Waal's constants. Also write their units.

The term that corrects for the attractive forces present in a real gas in the van der Waal's equation is

The term that is correct for the attractive forces present in a real gas in the van der Waals equation is

The constant 'a' in van der Waal's equation is maximum in