Three gases, one consisting of monatomic molecules, the second consisting of diatomic molecules, and the third consisting of polyatomic molecules, are in thermal equilibrium with each other and remain in thermal equilibrium as the temperature is raised.All have the same number of molecules.The gases with the least and greatest internal energy are respectively:
A)polyatomic, monatomic
B)monatomic, polyatomic
C)diatomic, monatomic
D)polyatomic, diatomic
E)all have equal internal energy

Question

Quizplus · Accepted Answer

Monatomic molecules have the least internal energy because they have the lowest number of degrees of freedom (3 translational only). Polyatomic molecules have the greatest internal energy because they have the highest number of degrees of freedom (3 translational + 2 rotational + vibrational). As the temperature is raised, all gases will gain internal energy, but the relative difference between the three types of molecules will remain the same. Therefore, the answer is B: monatomic has the least internal energy and polyatomic has the greatest.

Three Gases, One Consisting of Monatomic Molecules, the Second Consisting