Answer:
3. number of protons
Explanation:
In a neutral atom, the total number of electrons in such an atom is equal to the number of protons.
There are three fundamentally known sub-atomic particles in an atom. They are:
Protons which are positively charged and are contained in the nucleus
Neutrons which do not carry any charges
Electrons which are negatively charged.
Both of protons and neutrons are located in the nucleus.
Atoms are charged by gaining of losing electrons.
When an atom gains electrons, they become negatively charged and the number of electrons in them becomes more than that of protons.
When they lose electrons, they become positively charged as the the number of protons is more.
Neutral atoms have equal number of protons and electrons in them.
