1. An ideal gas undergoes an adiabatic expansion, a process in which no heat flows into or out of the gas. As a result,
(a) The temperature of the gas remains constant and the pressure decreases.
(b) Both the temperature and pressure of the gas decrease.
(c) The temperature of the gas decreases and the pressure increases.
(d) Both the temperature and volume of the gas increase.
(e) Both the temperature and pressure of the gas increase.
2. A heat engine operates between a high temperature of about 600°C and a low temperature of about 300°C. What is the maximum theoretical efficiency for this engine?
(a) = 100%.
(b) ≈ 66%.
(c) ≈ 50%.
(d) ≈ 34%.
(e) Cannot be determined from the given information.