Chemistry Comparisons

Correct Answer: B. both have 8 protons

¹⁸O and O^-2 are both forms of oxygen. The former is an isotope and the latter is an ion. They do not have the same number of neutrons, as an isotope has a different number of neutrons. Likewise the ion does not have the same number of electrons as the isotope because the ion has gained 2 electrons from its neutral form. The only thing in common between an isotope and an ion is the number of protons. The number of protons within the nucleus of an element does not change.

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