Which of the following best describes how an anion is formed?

• A. An atom loses one or more neutrons.
• B. An atom loses one or more electrons.
• C. An atom gains one or more electrons.
• D. An atom gains one or more protons.

Answer: (C)

Verified step by step guidance

1. Understand that an ion is an atom or molecule that has gained or lost electrons, resulting in a net electrical charge.
2. Recall that an anion is a negatively charged ion, which means it has more electrons than protons.
3. Recognize that gaining electrons increases the negative charge of the atom, forming an anion.
4. Note that losing electrons would create a positively charged ion called a cation, not an anion.
5. Conclude that the correct description of an anion formation is: an atom gains one or more electrons.