Assuming air to be a calorically perfect gas.
Given as: mass(m)=1Kg, Volume (V)=0.05m2
By ideal gas equation:
T=(20x105x0.05)/287 =348.43 K
Internal energy (U1)=mCvT=1x714x3484.3=248.780 k J
If internal energy is increased by 120 kJ
Given as P2=50x105Pa