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为了扩大知识面,下面介绍一种解计算型选择题或填空题的方法.这种方法简化思路,运算简便,解题迅速,结果准确.一有关溶液质量分数改变的选择题或填空题.[例1]有A克某物质的溶液质量分数为30%,若将其溶液质量分数改变为60%,可采用的方法是A、蒸发掉A/2克溶剂;B、蒸发溶剂的1/2;C、加入3/4A克溶质;D、加入A/2克溶质.解(一):设应蒸发掉溶剂为x克.30%溶液A克
In order to expand the scope of knowledge, the following describes a method to solve the computational multiple choice or fill in the blank. This method simplifies the idea, the operation is simple, the problem solving is rapid, and the result is accurate. A multiple-choice question or fill in the empty questions about the change of the solution mass fraction.[ Example 1] There are 3 grams of a solution of A substance. If the mass fraction of the solution is changed to 60%, A can be used to evaporate A/2 grams of solvent. B. Evaporate the solvent by 1/2 C, add 3/4A grams of solute; D, add A/2 grams of solute. Solution (I): set to evaporate the solvent as x g. 30% solution A g