Question

what does the document suggest about the mass of atoms? it is always changing. it is visible and easily measured. it is not visible. it is not related to the type of atom.

Explanation:

Atoms are extremely small particles. Their mass is an inherent property that is not visible to the naked - eye. The mass of an atom is related to the type of atom (as different atoms have different numbers of protons, neutrons, and electrons). Atoms do not have mass that is always changing under normal conditions, and while their mass can be measured, it is not easily measured in a casual sense.

Answer:

It is not visible.