Basicity is 1?? I was studying about Volumetric Analysis. In the chapter, there is a table which shows basicity of some acids. One is H3PO2. Its basicity is given as 1. But basicity of an acid is number of replacable hydrogen atoms present in one molecule of acid. So, bascitiy of H3PO2 should be 3. But that's not true according to book. It is 1.