问题 选择题

设NA表示阿伏加德罗常数,下列说法正确的是(   )

A.18 g H2O中所含的电子总数为10NA

B.1 L 1 mol·L-1的盐酸中含有的HCl分子数为NA

C.1 mol I2晶体完全升华后所得气体的体积约为22.4 L

D.常温下44 g Na2O2中含有O2-的数目为2NA

答案

答案:A

18 g水中水分子为1摩,每个分子中电子数为10个,所以A项是正确的;B项中的盐酸完全电离后溶液中没有氯化氢分子;C项中1摩气体只有在标准状况下的体积才是22.4 L;D项过氧化钠中没有O2-,只有

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Here are some patients(病人), each of whom wants to see a doctor . Decide which doctor is suitable for the patient mentioned. There is an extra doctor that is not suitable for any of the patients.

1. _____ Patient one. He has a running nose all day. He has a fever and constant cough.

2. _____ Patient two . She sleeps poorly . She has difficulty in sleeping , and is unable to concentrate. She also has nightmares(恶梦)occasionally.

3. _____ Patient three. His tongue is red and sore (痛) all over . His breath smells bad and he has

a bad taste in his mouth .

4. _____ Patient four. His blood pressure is really high. His head aches when he bends over or lies down.

A.Brown , a medical student majoring in oral cavity (口腔), is having his practice in a teaching hospital . Every day he meets quite a few people with a toothache , throat trouble and so on.

B.Tom is a psychologist (心理学家) . He keeps in touch with his mental patients by phone.

C.Wood , an adviser and doctor in a hospital , thinks we should pay more attention to what we eat . It is a problem that many people are becoming fatter and fatter. In his opinion, blood pressure is connected with it and he is trying his best to solve this kind of problem.

D.Mary , a female doctor , is doing research in breast-cancer . A lot of woman , she thinks , are suffering from this kind of disease all over the world . She has made up her mind to help these women.E. Mr. Smith is a very good physician. He works as a doctor in a hospital and he is an expert at curing common diseases .It is easy and convenient to see Mr. Smith.