Rank the following oxyanions in order of increasing basicity based on the acid-dissociation constants (Ka) given below: SeO32–, AsO43–, SeO42–, and CrO42–.
H2SeO3: Ka1 = 2.3×10–3, Ka2 = 5.3×10–9
H3AsO4: Ka1 = 5.6×10–3, Ka2 = 1.0×10–7, Ka3 = 3.0×10–12
H2SeO4: Ka1 = very large, Ka2 = 2.2×10–2
H2CrO4: Ka1 = 1.8×10–1, Ka2 = 3.0×10–7
