It is known as the melting point
Answer:
the structure of an atom, theoretically consisting of a positively charged nucleus surrounded and neutralized by negatively charged electrons revolving in orbits at varying distances from the nucleus, the constitution of the nucleus and the arrangement of the electrons differing with various chemical elements.
Explanation:
A. Oxygen ion
I am not sure but that's the right one I think. If I am wrong then I am sorry
