$N$ Molecules of a Monatomic Gas $A$ Are Mixed with the Same Number of Molecules of a the Same

Multiple Choice

$N$ molecules of a monatomic gas $A$ are mixed with the same number of molecules of a diatomic gas $B$ in a container, and the mixture is held at a constant temperature $T$ (which is about equal to room temperature) . The molecules of gas $A$ have mass $m_{A}$ , and the molecules of gas $B$ have mass $m_{B}>m_{A}$ Which gas has In each case, choose from one of the four answers below.
-(c) the greater total thermal energy $U$ , and

A) The quantity is greater for gas $A$ .
B) The quantity is greater for gas $B$ .
C) The quantity is the same for both gases.
D) One does not know enough to compare the quantities.