问题 选择题

用NA表示阿佛加德罗常数,下列说法中正确的是

A.1mol甲烷的质量与NA个甲烷分子的质量之和相等

B.28g氮气与40g氩气所含的原子数目相等,都是NA

C.2.3g钠由原子变成离子,失去的电子数为0.1NA

D.18g重水(D2O)所含的电子数为10NA

答案

AC

根据摩尔的定义,每摩尔物质含有阿伏加德罗常数(NA)个微粒,所以A组答案是正确的,氮气是双原子分子,而氩气是单原子分子,28g氮气所含有的原子数为2NA个,40g氩气所含的原子数目是NA个;一个钠由原子变成离子时,将会失去1个电子,2.3g钠为0.1mol,由原子变成离子时失去的电子数为0.1NA;18g重水(D2O)所含的分子为0.9mol,而每个分子所含的电子数为10个,所以18g重水(D2O)所含的电子数为9NA;故答案为AC

阅读理解

阅读理解。(每小题2分,共30分)

阅读下列材料,从 A、B、C、D 四个选项中选出最佳答案,并把答题卡上对应题目的答案标号涂黑。

A

People say that George Washington, the first president of the United States, never told a lie. But it seems that the president was not without faults.

A New York library recently found that Washington borrowed two books from the library in 1789. He didn’t return them.

If he were still alive, he would have to pay the library $300,000 for being 220 years late.

On October 5, 1789, when the first president borrowed the books form the New York Society Library, he didn’t sign his name in the borrower’s book. He just wrote “president” to show who had taken them out.

The two books should have been brought back a month later but were never returned. Workers at the library realized the books were missing.

The New York Society Library doesn’t expect anyone to pay the fine. But it hopes that someone will return the books.

小题1:Gorge Washington is__________.

A.the president of the US now

B.the first president of the US

C.the first black president of the US

D.the president who always borrowed the books without returning them back小题2:Gorge Washington borrowed a book from ________.

A.the Washington Public Library

B.the New York Society Library

C.the Paris Society Library

D.the Chinese Public Library小题3:The library hopes _________.

A.Gorge Washington will return the book.

B.Gorge Washington will pay the fine

C.someone will find the book and return it

D.someone will pay the fine for the president

单项选择题