20 g/cm3 I got this because 120 divided by 6 is 20
Answer:
The nuclei of most atoms also contain neutrons . The masses of subatomic particles are very tiny. ... Since the nucleus contains protons and neutrons, most of the mass of an atom is concentrated in its nucleus. Protons and electrons have electrical charges that are equal and opposite.
A . O2- because it is a negatively charged ion
