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九年级化学在第四单元学习完以后,学生常会遇到有关物质化学式确定的问题,下面我举一例子X,Y两种元素可形成两种化合物A和B,在A中X元素的质量分数为75%,在B中X的
After the completion of the fourth unit in the ninth grade chemistry, students often encounter problems with the determination of the chemical formula of the substance. Let me give an example. X and Y can form two compounds A and B. The mass fraction of the X element in A. Is 75% in B in X’s