Answer:
An isothermal process (change)
Step-by-step explanation:
The initial volume of the gas, V₁ = 15 L
The initial volume of the gas, V₂ = 39 L
The amount of work it performs, W = 1.8 kJ
For the above change, the initial and final pressure of the gas can be calculated, using Boyle's law which is based on an isothermal change process as follows;
P₁·V₁ = P₂·V₂
P ∝ 1/T