问题 选择题

C三的一位同学根据所学知识设计了下列物质的区别方法,您认为错误的是(   )

A.区别氧气和氮气,选择带火星的木条

B.区别二氧化碳和氮气,将气体分别通入紫色石蕊溶液中

C.区别二氧化碳和氮气,选择燃着的木条

D.区别氧气和二氧化碳,将气体分别通入澄清的石灰水中

答案

答案:C

题目分析:氧气、氮气和二氧化碳都是无色气体,氧气能使带火星的木条复燃;二氧化碳能使澄清石灰水变浑浊;氮气性质温度,一般条件下不易发生反应。氮气和二氧化碳都不能燃烧也不支持燃烧,燃着的木条遇到它们都会熄灭。题中C说法错误。

点评:鉴别物质的主要依据是物质的性质。

多项选择题
阅读理解

阅读理解。

     Mr. and Mrs. Smith had always spent their summer holidays in New Jersey in the past, staying in a small

inn at the foot of a hill. One year, however, Mr. Smith made a lot of money in his business, so they decided

to go to London and stay at a really good hotel while they went t turning around that famous city.

     They flew to London and arrived at their hotel late one evening. They expected that they would have to

go bed hungry, because in that small inn in New Jersey, no meals served after seven. They were therefore

surprised when the man who received them in the hall asked whether they would take dinner there that night.

     "Are you still serving dinner?" asked Mr. Smith.

     "Yes,certainly, sir," answered the man. "We serve it until half past nine."

     "What are the times of meals then?" asked Mr. Smith.

     "Well, sir," answered the man. "We sever breakfast from seven to half past eleven in the morning, lunch

from twelve to three in the afternoon, tea from four to five, and dinner from six to half past nine."

     "But that hardly leaves any time for us to see the sights of London!" said Mrs. Smith.

1. Mr. and Mrs. Smith had _____ in the past.

A. often stayed in a quite good hotel

B. often stayed in a small inn

C. travelled to many places

D. made a lot of money

2. They decided to go to a really good hotel because _____.

A. it was said to be a quite good one

B. they were tired of small inns

C. it was near many places of interest

D. they now had enough money

3. When they got to the hotel, _____.

A. no meals wre served after seven

B. dinner was still being severed

C. there wre no visitors

D. the waiters were asleep

4. Mrs. Smith _____.

A. would have lots of time to see the sights

B. was afraid that they would have no time to tour around London

C. thought the hotel wasn't so good as they expected

D. did know why the hotel was better than the small inn