题干

下列除去杂质的方法正确的是(   )

A:除去N2中的少量O2:通过灼热的CuO粉末,收集气体

B:除去CaO中的少量CaCO3:加入足量稀盐酸,充分反应

C:除去KCl溶液中的少量MgCl2:加入适量NaOH溶液,过滤

D:除去Cu(NO32溶液中的少量AgNO3:加入足量铜粉,充分反应后过滤

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答案(点此获取答案解析)

D

同类题1

Fill in the blanks with proper words(在短文的空格内填入适当的词,使其内容通顺。每空格限填一词,首字母已给)

explains      common    used    change      besides     usually 

    ZhangMing, a college graduate from Shandong, created a 9-page"Wechatguide". With drawings and simple words, the step-by-step guide e____ how to send messages, take pictures and make video calls. Zhang made the guide for his parents. "My parents are getting old. They need an easy way to learn how to use technology, "he said.

    Zhang's experience is c____ nowadays.Worldwide,40percent of parents learn about new technologies, including computers, mobile Internet and social media, from their children, according to a study from the International Communication Association in 2017.

    Parents u ____ to teach their kids about almost everything. Now for the first time, the teachers become the students, and the students turn into the teachers.

    The c____ of the roles comes from the rapid development of society and technology says Zhou Xiaohong, a sociology professor from Nanjing University. Zhou said the Internet and other forms of media give children ways to get information b____  from asking older generations. Therefore, in the age of information, it's possible that children know more than their parents do.

    According to the China Internet Network Information Center, 56.7 percent of Internet users and 67.2 percent of social media users in China are under the age of 30. The younger generation u____ acts as a link between their family and the new environment. But when they teach their parents new technologies, parents can connect to the new world by themselves, noted Zhou.

    In Zhang Ming's eyes, teaching his parents about Wechat brings him c____ to his parents."People can communicate more by using new technology. Why should we keep our parents out? "said Zhang.