题干

设NA为阿伏伽德罗常数的值.下列说法正确的是(   )

A:标准状况下,11.2 L CCl4中含有的分子数为0.5NA

B:在Na2O2与水的反应中,每生成1 mol O2,转移电子的数为2NA

C:常温常压下,7.8 g苯中含有双键的数目为0.3NA

D:25℃时,0.1 mol•L﹣1 NH4NO3溶液中含有的铵根离子数为0.1NA

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答案(点此获取答案解析)

B

同类题3

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    For college students, graduation signals an exciting new beginning. ____ Many students wonder: What do I do now? What career is best for me? Most expert advice on choosing careers boils down to the following points.

Knowing Yourself

    What are your interests? Abilities? Skills? ____ The results may surprise you! These can be useful, but they're not the last word.

Investigating

    Investigating occupations is much more difficult. For most people, there isn't just one ‘right' job, but several that could be satisfying. ____ Talk to people who have occupations that interest you. Find out what they like and dislike about their job.

____

    Many people choose their careers because they believe strongly in a particular cause. Some might choose to work in areas like medicine, charity or environmental protection. Some have a strong interest in history or a love for the arts. ____ So in cases like these, the field is often chosen first, rather than the occupation itself. So if you've chosen a field, self-assessment will help you find your place in it. Invest some time and effort, and find the right career for you.

A. Try a self-assessment quiz.

B. Search through books and Web sites.

C. Finding your place.

D. But it can also bring a lot of uncertainty and confusion.

E. Serious research helps narrow the possibilities

F. Research your chosen field carefully. What work needs to be done? What training is needed?

G. Then they might think about education, museums or art production.