The internal energy of a substance is dependent on its kinetic and potential energies. If the internal energy of gas was to decrease then it would result in the potential energy decreasing and leading to a phase change. The phase change would be from a gas to a liquid - so condensation.
The phase could change from a gas to a solid but desublimation isn't an option
The internal energy of a substance is dependent on its kinetic and potential energies. If the internal energy of gas was to decrease then it would result in the potential energy decreasing and leading to a phase change. The phase change would be from a gas to a liquid - so condensation.
The phase could change from a gas to a solid but desublimation isn't an option