有一混合物是由盐酸、碳酸钠、硝酸钾、硫酸和氯化铜中的两种溶液混合而成．向该混合溶液中滴加氢氧化钡溶液，溶液体积的变化与生成沉淀质量的关系如右图所示，那么，这两种溶液是
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A．盐酸、硫酸
B．碳酸钠、硝酸钾
C．硝酸钾、盐酸
D．盐酸、氯化铜
A、盐酸与硫酸中加入Ba（OH）2后，反应开始时硫酸会与之生成硫酸钡沉淀产生．与给出的曲线不符．故A不适合；
B、碳酸钠与硝酸钾中加入氢氧化钡，碳酸钠会与之反应生成碳酸钡的白色沉淀，且一开始就会产生，与给出的曲线不符，故B不合适．
C、当Ba（OH）2滴入硝酸钾与盐酸混合溶液中，不会发生反应生成沉淀，所以与给出的曲线不符．故C都不适合；
D、把氢氧化钡加入到盐酸与氯化铜的溶液中，氢氧化钡能与两者都反应，当盐酸消耗完了以后，才会与氯化铜反应生成氢氧化铜的沉淀，与图象所示的沉淀情况相符．故D适合．
故选D．
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