12. an example of an atom that has no charge is one that has a. 3 protons, 1 electron, and 3 neutrons. b. 3 protons, 2 electrons, and 1 neutron. c. 1 proton, 2 electrons, and 3 neutrons. d. 2 protons, 2 electrons, and 1 neutron.

[D. 2 protons, 2 electrons, and 1 neutron.]

As we know that, protons are embedded in the nucleus with neutron having no charge. So, nucleus has positive charge. Electrons are revolved around the nucleus of the atom. Proton has positive charge and electron has negative charge.

Number of proton = Number of electron.

Hence, both 2 protons and 2 electrons make the atom electrically neutral. So, the net charge of atom is 0. Neutron are the subatomic particle which has only mass.