Which of the following is a triprotic acid?

• A. H2CO3 (carbonic acid)
• B. H3PO4 (phosphoric acid)
• C. H2SO4 (sulfuric acid)
• D. HNO3 (nitric acid)

Answer: (B)

Verified step by step guidance

1. Understand that a triprotic acid is an acid that can donate three protons (H\textsuperscript{+} ions) per molecule in an acid-base reaction.
2. Examine each acid's chemical formula to determine how many acidic protons it contains: H\_2CO\_3 (carbonic acid) has 2 acidic hydrogens, H\_3PO\_4 (phosphoric acid) has 3 acidic hydrogens, H\_2SO\_4 (sulfuric acid) has 2 acidic hydrogens, and HNO\_3 (nitric acid) has 1 acidic hydrogen.
3. Recall that the number of acidic hydrogens corresponds to the number of protons the acid can donate, so the acid with 3 acidic hydrogens is triprotic.
4. Identify H\_3PO\_4 (phosphoric acid) as the acid with three ionizable protons, making it triprotic.
5. Confirm that the other acids are not triprotic because they have fewer than three ionizable protons.