Number of collisions per second of molecules of a gas on the wall of a container per m2 will:
(2,3)
No. of collisions per unit area∝1time between two collisions×area
nA∝Vrmsdistance b/w walls×A Vrms∝T Distance b/w walls×A=volume
So nA∝T1/2V
If both T and V are halved, nA increases.