Which of the following ions is classified as a cation?

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

Answer: (C)

Verified step by step guidance

1. Understand the definition of a cation: a cation is a positively charged ion, meaning it has more protons than electrons and carries a positive charge.
2. Look at each ion's charge notation to determine if it is positive or negative. For example, \(\mathrm{NO_3^-}\) has a negative charge indicated by the superscript minus sign.
3. Identify the charge on each ion: \(\mathrm{NO_3^-}\) (nitrate) is negatively charged, \(\mathrm{SO_4^{2-}}\) (sulfate) is doubly negatively charged, \(\mathrm{Na^+}\) (sodium ion) is positively charged, and \(\mathrm{Cl^-}\) (chloride) is negatively charged.
4. Since cations are positively charged, select the ion with a positive charge, which is \(\mathrm{Na^+}\) in this list.
5. Confirm that all other ions are anions (negatively charged), so \(\mathrm{Na^+}\) is the only cation among the options.