Doubt from thermodynamics

Q 24
Ans: final pressure 3.210^4 PA
Work done=1.52

After the stop cock is opened the free expansion happens and temp. remained constant (isothermal).

I am not getting any answer near to exact value.
By applying adiabatic condition T=300/sq rt(2) =212.. And somewhat nearer ans for pressure if we use 224K

Can you try once and share your answer?

I am also getting the same as yours