Answer:
The answer to your question is 1m/sec.
Step-by-step explanation:
The velocity of a molecule in a vacuum is 1m/sec.
Under lower and lower pressure, the molecules spread out further and further, until, at ultra-high vacuum (10 -12 mbar), there are only 2.65 x 104 or 26,500 molecules per cubic centimeter. At this density, there is only one molecule roughly every 0.33 mm in space.
I hope this helps and have a wonderful day!