Which best describes the motion of molecules in the gaseous state?
a. they vibrate quickly in place.
b. they spread apart to fill their container.
c. they move at the same speed as in a liquid.
d. they move slowly over one another.

The statement that best describes the motion of molecules in the gaseous state is they spread apart to fill their container.

Option B

Explanation:

For the matter to vibrate in its place, it has to be in the liquid state. Gas molecules are widely spaced and fail to hold up together in one place. For example,

a spray of steam in a glass container would quickly show up on the walls of the container on all sides. Gases usually move fast in empty spaces than in any other matter.

quote is the answer your looking for.