Which of the following ions is a cation?

• A. Cl^-
• B. SO_4^{2-}
• C. NO_3^-
• D. Na^+

Answer: (D)

Verified step by step guidance

1. Understand the definition of a cation: a cation is a positively charged ion, meaning it has lost one or more electrons.
2. Look at the charge of each ion given in the problem: Cl⁻ has a negative charge, SO₄²⁻ has a negative charge, and NO₃⁻ also has a negative charge.
3. Since all the ions listed (Cl⁻, SO₄²⁻, NO₃⁻) have negative charges, they are all anions, not cations.
4. Identify the ion Na⁺, which has a positive charge, indicating it is a cation because it has lost one electron.
5. Conclude that among the options, Na⁺ is the cation because it carries a positive charge, while the others are anions with negative charges.