The total number of electrons in a neutral atom of every element is always equal to the atom's
1. mass number
2.
number of neutrons
3.
number of protons
4.
number of nucleons

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.