**(A):** is a dibasic acid. <br> **(R):** It contains two replaceable atoms. — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

**Assertion:** Although it contains three hydrogen atoms, phosphorous acid ($H_3PO_3$) only has two acidic protons. Statement is true. <br>**Reason:** The structure contains two $P-OH$ bonds and one $P-H$ bond. Only hydrogens attached to oxygen (highly electronegative) are ionizable. This explains its dibasic nature.