Answer:

Step-by-step explanation:
By using the first law of thermodynamics, we can find the work done by the gas:

where in this problem:
is the change in internal energy of the gas
is the heat absorbed by the gas
W is the work done by the gas (positive if done by the gas, negative otherwise)
Therefore, solving for W,

So, the gas has done positive work: it means it is expanding.
Then we can rewrite the work done by the gas as

where:
is the pressure of the gas
is the initial volume of the gas
is the final volume
And solving for Vf, we find
