Which acid is the best choice to create a buffer with pH=pH= 2.07? Which acid is the best choice to create a buffer with 2.07? chlorous acid (HClO2),pKa=1.95(HClO2),pKa=1.95 hypochlorous acid (HClO),pKa=7.54(HClO),pKa=7.54 nitrous acid (HNO2),pKa=3.34(HNO2),pKa=3.34 acetic acid (HCH3CO2),pKa=4.76

The best choice to create a buffer with pH = 2.07 is chlorous acid

Explanation:

To choose the pH of a buffer you must know that the nearest pH to pKa of the buffer, the better buffer capacity (quantitative measure of the resistance to change of pH of a buffer)

If you see, in the problem, the acid that has the pKa nearest to desire pH (2.07), is chlorous acid (HClO₂; pKa = 1.95). Thus, the best choice to create a buffer with pH = 2.07 is chlorous acid.