Which of the following aqueous solutions are good buffer systems?
0.25 M ammonium nitrate + 0.40 M ammonia
0.23 M nitric acid + 0.20 M sodium nitrate
0.16 M potassium hydroxide + 0.22 M potassium chloride
0.39 M hypochlorous acid + 0.25 M potassium hypochlorite
0.12 M hydrofluoric acid + 0.14 M sodium fluoride