[ian123]

I am stuck on question QA2(e).
I know that there is no work on the gas by the piston because the pressure remains constant. But there is, however, a heat transfer to the system which means that Q1=750J.
I used this equation
heat transferred or Q=ncv(T2-T1)+W1-2=750J
And solved it from there.
But it doesn't seem to work.
The right answer is 493.8K. But I don't know how to get this.
 
Help will be greatly appreciated. Thank you.

[Enthalpy]

I know that there is no work on the gas by the piston because the pressure remains constant.

I doubt that one. A force on a moving object uses to make work.