試題詳解

32. For an ideal diatomic gas (let us treat them as non-rigid rotators), there are N molecules confined to a two-dimensional space of area A, as shown in the figure below. These diatomic molecules can only rotate in the plane (i.e., with angular velocity perpendicular to the plane), but are allowed to translate and vibrate in the two-dimensional plane. In thermal equilibrium at a temperature T (assuming that T is high enough so that the gas can be handled classically), which of the following statements is true?

(A)The internal energy of the ideal diatomic gas is 2Nk_BT.
(B)The internal energy of the ideal diatomic gas is 5Nk_BT/2.
(C)The total rotational kinetic energy is greater than the total translational energy.
(D)The total rotational kinetic energy is greater than the total vibrational energy.
(E)The speed distribution is the same Maxwell-Boltzmann distribution for the ideal monatomic gas in three dimensions.