Which of the following aqueous solutions are good buffer systems? . 0.21 M hydrofluoric acid + 0.15 M sodium fluoride 0.34 M sodium iodide + 0.25 M sodium perchlorate 0.19 M sodium hydroxide + 0.26 M sodium bromide 0.30 M ammonia + 0.33 M ammonium nitrate 0.26 M perchloric acid + 0.16 M sodium perchlorate