Which of the following terms are needed to completely describe speed? Check all that apply.
A. Direction
B. Units
C. Mass
D. Number

c. and a

Explanation:

if they have a finite resultant

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.