Question

There is no atmosphere on moon as

• A. It is closer to earth.
• B. It revolves around the earth.
• C. It gets light from the sun.
• D. The rms speed of gas molecules is greater than the escape speed.

Answer 1

Answer: (D)

The rms speed of gas molecules is greater than the escape speed.

Answer 2

Moon has no atmosphere because the rms speed of gas molecules is greater than the escape speed

(i.e., $v _ { \mathrm { rms } } > \mathrm { v } _ { \mathrm { e } }$ ).