An ideal gas is confined to the left chamber of an insulated container.
The right chamber is evacuated. A valve is opened between the chambers, allowing gas to flow into the right chamber. After equilibrium is established, the temperature of the gas ______.
(a) Is lower than the initial temperature
(b) Is higher than the initial temperature
(c) Is the same as the initial temperature
(d) Could be higher than, the same as, or lower than the initial temperature