Which of the following is the correct chemical formula for chlorous acid?

• A. $HClO$
• B. $HCl{O}_4$
• C. $HCl{O}_3$
• D. $HCl{O}_2$

Answer: (D)

Verified step by step guidance

1. Understand that chlorous acid is an oxyacid of chlorine, where chlorine is bonded to oxygen and hydrogen.
2. Recall the naming convention for chlorine oxyacids: 'hypochlorous acid' corresponds to HClO, 'chlorous acid' corresponds to HClO₂, 'chloric acid' corresponds to HClO₃, and 'perchloric acid' corresponds to HClO₄.
3. Identify that the suffix '-ous' in chlorous acid indicates the acid with chlorine in the +3 oxidation state, which corresponds to the formula HClO₂.
4. Compare the given options with the known formulas for chlorine oxyacids to find the one matching HClO₂.
5. Select the formula HClO₂ as the correct chemical formula for chlorous acid.