vander waaals equation of state,
where 'a' states that greater the value of 'a' more easily thr gas is liquefiable,
critical temperature,
T
C=8a/27b
Here T is directly proportional to a,hence more the value of 'a' more greater critical temperature
T1=250K
T2=125K
T1>T2
a1>a2
Hence gas 1 will change into liquid before gas 2
Hope this helps you..!!