An ideal gas undergoes a process in which its volume stays fixed while its pressure decreases steadily. Which of the following is most consistent with this description?
(a) The process is isothermal, so the change in internal energy of the gas is zero.
(b) The process is isobaric, so the work done by the gas equals PΔV.},{
(c) The process is isochoric, so the work done by the gas is zero.
(d) The process is adiabatic, so no heat is exchanged and the work done on the gas is zero.