问题 选择题

标准状况下,两个容积相等 的贮气瓶,一个装有O2,另一个装有CH4,两瓶气体具有相同的(  )

A.质量

B.原子总数

C.密度

D.分子数

答案

答案:D

题目分析:根据阿伏加德罗定律可知,氧气和甲烷的物质的量相等,分子数也相等。由于氧气是2个氧原子构成的,甲烷是5个原子构成的,所以原子数不同。氧气和甲烷的相对分子质量不同,二者的质量和密度不同,答案选D。

点评:该题是中等难度的试题,试题注重基础,侧重能力的培养和解题方法的指导。有利于培养学生的逻辑思维能力和抽象思维能力,提高学生分析问题、解决问题的能力。

单项选择题
单项选择题

When Dave was eighteen, he bought a secondhand car for 200 so that he could travel to and from work more (1) than by bus. It worked quite well for a few years, but then it got so old, and it was costing him (2) much in repairs that he decided that he had better (3) it.

He asked among his friends to see if anyone was particularly (4) to buy a cheap car, but they all knew that it was falling to pieces, so (5) of them had any desire to buy it. Dave’s friend Sam saw that he was (6) when they met one evening, and said, "What’s (7) , Dave"

Dave told him, and Sam answered, "Well, what about advertising it in the paper You may (8) more for it that way than the cost of the advertisement!" Thinking that Sam’s (9) was sensible, he put an advertisement in an evening paper, which read "For sale: small car, (10) very little petrol, only two owners. Bargain at 50. " For two days after the advertisement first appeared, there was no (11) . But then on Saturday evening he had an enquiry. A man rang up and said he would like to (12) him about the car. "All right, " Dave said, feeling happy. He asked the man whether ten o’clock the next morning would be (13) or not. "Fine, " the man said, "and I’ll (14) my wife. We intend to go for a ride in it to (15) it. "

The next morning, at a quarter to ten, Dave parked the car in the square outside his front door, (16) to wait there for the people who had (17) his advertisement. Even Dave had to (18) that the car really looked like a wreck. Then, soon after he had got the car as clean (19) it could be, a police car stopped just behind him and a policeman got out. He looked at Dave’s car and then said, "Have you reported this (20) to us yet, sir\

14().

A.follow 

B.meet 

C.bring 

D.introduce