I think that it is helium, but not 100% sure
B and/or C because velocity is also know as a vector quantity and speed is a scalar quantity
Answer:
okay so i hope this helps
Explanation:
In chemistry and physics, the atomic theory explains how our understanding of the atom has changed over time. Atoms were once thought to be the smallest pieces of matter. However, it is now known that atoms are made up of protons, neutrons, and electrons. These subatomic particles are made up of quarks.