1/5单选题
难度：
1.
将碳酸钠和硫酸钠的固体混合物6g，放入烧杯中，再加入一定量的稀硫酸，在一定时间内恰好完全反应，无固体剩余，所得溶液溶质质量分数为19.5%，反应的时间(t)和烧杯及其所盛物质总质量(m)的关系如下图所示：求所加稀硫酸的溶质质质量分数为
| A | 10.5% |
| B | 11.5% |
| C | 12.5% |
| D | 13.5% |
正确答案：RA==
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
取废液桶上层清液共11.88kg，向其中加入溶质质量分数为21.2％的碳酸钠溶液。所得溶液pH与加入的碳酸钠溶液的质量关系如上图所示：废液恰好处理完(盐酸与氯化钙的混合溶液完全转化成氯化钠溶液)时所得溶液能否用于该校生物兴趣小组的小麦选种(选种液要求氯化钠的溶质质量分数在(10％一20％之间)其质量分数是多少？