Which gas exerts a greater pressure?

[s3a]

Question

13. Which of the two gases, Cl2 or Ar, exerts a greater pressure when one mole of gas is
placed in a 10.0 L container at 25.0 oC? [ P(Cl2) > P(Ar) ]

a / atm·L2·mol-2 b / L·mol-1
DATA:
Cl2 6.49 0.562
Ar 1.35 0.0322

I'm stuck on this question and do not know what to do!

Any help would be greatly appreciated!
Thanks in advance!

[Sonic]

I would suggest the Van der Waal's equation since both a and b are given

(p+[n^2*a/V^2])*(V-nb) = nRT

p is pressure
n is number of moles
a is a in the question
V is volume
b is b in the question
R is the ideal gas constant
T is temperature in K