今欲配制一升0.01000mol/LK2Cr2O7(摩尔质量294.2g/mol)溶液.所用分析天平的准确度为±0.1mg 若相

职业资格 准确度,溶液,天平 已帮助

今欲配制一升0.01000mol/LK2Cr2O7(摩尔质量294.2g/mol)溶液.所用分析天平的准确度为±0.1mg,若相对误差要求为±0.2%,则称取K2Cr2O7应称准至:()

A.0.1g

B.0.01g

C.0.001g

D.0.0001g

E.0.02g

请帮忙给出正确答案和分析,谢谢!


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