Which of the following is an example of a cation?

A cation is defined as a positively charged ion, meaning it has more protons than electrons. Sodium is a classic example of a cation. When sodium (Na) loses an electron, it becomes a Na⁺ ion, acquiring a positive charge in the process. This is fundamental to its role in numerous biological processes, such as nerve impulse transmission and muscle contraction.

In contrast, the other options provided are anions, which are negatively charged ions. Chloride (Cl⁻) and sulfate (SO₄²⁻) both gain electrons to achieve a negative charge, while phosphate (PO₄³⁻) also becomes negatively charged by gaining electrons. Understanding the distinction between cations and anions is crucial in fields like biochemistry, pharmacology, and dermatology, as it affects how different compounds interact within the body, including their roles in skin health and function.