有关金属与盐所发生的置换反应一直是中考的热点,其中把一种金属放入两种盐的混合溶液中和把两种金属放入同一种盐溶液中所发生的有关反应,又是该考点的重点和难点．下面举两例加以解析．例1 在CuSO4和FeSO4的混合溶液中加入Mg粉,下列说法错误的是( ) (A)若Mg粉有剩余,溶液中只有Fe2+,而 The displacement reaction between metals and salts has been a hot topic in the examination, where a metal is placed in a mixed solution of two salts and the reaction occurs when the two metals are placed in the same salt solution. The focus and difficulty of the test center. Here are two examples to be resolved. Example 1 Mg powder was added to the mixed solution of CuSO4 and FeSO4. The following statement is erroneous () (A) If there is a surplus of Mg powder, there is only Fe2+ in the solution.