a. The moon's escape velocity is small and allows molecules to escape very easily. b. Hydrogen could more easily reach escape velocity than other gases.
Work Step by Step
a. Any atmosphere that the moon may once have had escaped long ago. The escape velocity for the Moon is about 0.2 that of the Earth, so even heavy molecules, with lower speeds, can get away. b. Hydrogen is the lightest gas. At any given temperature, hydrogen atoms have a higher speed than any other gas. Hydrogen would be the first to escape the clutches of Earth’s gravity.