The three sentence summary of the document is:
The document contains a quick quiz with questions about ions, isotopes, and the number of protons, electrons and neutrons in different atomic species including chloride ion, argon, potassium ion, magnesium ion, sulfur and cobalt. The questions test knowledge of identifying anions, cations, isotopes and isoelectronic species as well as determining the number of protons, electrons and neutrons in different atoms and ions.