What is the solution method?

4. The critical temperatures and pressures of NO and CC4 are 172K and 64atm, and 550K and 45atm, respectively. a) Which gas has the lowest Van der Waals constant "b"? b) Which gas has the lowest Van der Waals constant "a"?? c) Which gas has higher critical volume? d) Which gas behaves more ideal at 300K and 10 atm conditions