A horizontal, frictionless cylinder is sealed at both ends and thermally insulated from its surroundings. A massless, frictionless piston in the center is attached to an ideal spring anchored to the left end. Initially, the piston is locked in place with the spring at its natural length; the left chamber contains an ideal gas at 600 K and the right chamber is a vacuum. The lock is released, allowing the piston to move until the system eventually settles with the gas filling the entire cylinder and the spring compressed. Which of the following correctly describes the changes occurring during this spontaneous process?
(a) The gas entropy remains unchanged, the spring’s potential energy increases, and the total internal energy of the isolated system remains constant.
(b) The gas entropy increases, the spring’s potential energy increases, and the total internal energy of the isolated system remains constant.
(c) The gas entropy increases, the spring’s potential energy increases, and the total internal energy of the isolated system decreases.
(d) The gas entropy decreases, the spring’s potential energy increases, and the total internal energy of the isolated system remains constant.