MgCl2溶液与Na2SO4溶液混合后，c(Mg2+)=c(
)，则下列说法不正确的是（ ）
A．混合液中c(Cl-)=c(Na+)
B．混合液中c(Cl-)=2c()
C．混合前两溶液体积相等
D．混合前两溶液中MgCl2与Na2SO4物质的量相等
答案：C
根据溶液电荷守恒，c(Na+)+2×c(Mg2+)=c(
)×2+c(Cl-)，又因为c(Mg2+)=c()，所以A正确。因为2c(Mg2+)=c(Cl-)，又因为c(Mg2+)=c()，所以B正确。混合后为同一溶液，体积相等，浓度相同，必然物质的量相同，所以D正确。
阅读短文，按要求完成后面的任务。 阅读下列短文，根据短文中的信息完成文后表格。（每空一词） Today, there are many problems between parents and children. Many people always ask, “ Why do we often argue(争论)?” Parents show their love to children in different ways. They cook nice food, buy new clothes for them. They also care about their studies. Parents always ask “ You must work hard”, “You should do your homework”, “Why not do homework for your exam?” all the time. When children get bad marks, their parents get very angry. They stop their children watching TV, playing games or going outside until they are good at their studies. Why? Most families have only one child. The child is the hope of the family, they want the child to be the best. Many children want to do things themselves. They want to do many unusual things that parents dislike. They like pop music, basketball and other new things. They enjoy surfing on the Internet and playing QQ games. They spend a lot of time chatting online and listening to the QQ music. In their parents’ eyes, these are a waste of time. For these reasons, parents and children often argue.
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