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【单选题】
测定(NH4)2SO4中的氮时,不能用NaOH标准溶液直接滴定,这是因为 ( )A.
N H 3 的 K b 太小
B.
(N H 4 ) 2 S O 4 不是酸
C.
NH 4 + 的 K a 太小
D.
(N H 4 ) 2 S O 4 中含游离 H 2 S O 4
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