Average translational KE of a He atom at 300 K is approximately ($k_B = 1.38 \times 10^{-23}$ J/K):
A$6.2 \times 10^{-21}$ J
B$6.2 \times 10^{-23}$ J
C$300 k_B$
D$1$ J
Answer & Solution
Correct answer: A. $6.2 \times 10^{-21}$ J
$\frac{3}{2} k_B T = \frac{3}{2} \times 1.38 \times 10^{-23} \times 300 \approx 6.21 \times 10^{-21}$ J per atom. Same for all monatomic gases at the same temperature.
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