Question

An example of an atom that has no change is one that has A. 1 proton, 2 electrons, and 3 neutrons B. 3 protons,2 electrons, and 1 neutron C. 2 protons, 2 electrons, and 1 neutron D. 3 protons, 1 electron, and 3 neutrons

Answer 1

Your question asks which is an example of an atom that has no change, or charge.

Your answer would be C). 2 protons, 2 electrons, and 1 neutron

These atoms would be known as a neutral atom.

In order for an atom to be neutral, it must have the same amount of protons and electrons.

We know that Protons are positive

We also know that Electrons are negative

In order for the atom to be neutral, they must have an equal amount of protons and neutrons to "cancel out"

In answer choice C, you would see that there are 2 protons and 2 electrons.

2- 0 = 0, in which allows this atom to be neutral.

Therefore, answer choice C. 2 protons, 2 electrons, and 1 neutron would be your answer.

Answer 2

I think you mean an atom that has "no charge".  I'll assume that, and then answer the question that I just invented:

That would be the (Helium) atom described in Choice-C .

Each proton has 1 positive charge, and each electron has 1 negative charge. So any atom that has equal numbers of protons and electrons is electrically neutral ... it looks like it has no charge at all.  Choice-C is the only one on the list that has equal numbers of protons and electrons.

(Neutrons have no charge at all.  So when you're working with the total charge on the atom, the neutrons don't make any difference.)