问题 选择题

下列混合物的分离方法不正确的是(  )

A.水和汽油的混合物用分液方法分离

B.石灰水中悬浮的固体碳酸钙用过滤方法分离

C.碘水中的碘用酒精萃取分离

D.乙醇中溶解微量食盐,用蒸馏方法分离

答案

答案:C

题目分析:A.水和汽油由于是互不相容的两种液态物质。所以它们的混合物用分液方法分离 。正确。B.固体碳酸钙不溶解于水,而Ca(OH)2能溶解于水中,所以石灰水中悬浮的固体碳酸钙用过滤的方法分离 。正确。C.碘在有机溶剂如苯、四氯化碳中的溶解度比在水中的大,而苯、四氯化碳与水又互不相容,所以可以用苯或四氯化碳作萃取剂来萃取分离。但是酒精与水互溶,因此碘水中的碘不能用酒精萃取分离 。错误。D.乙醇是分子构成的物质,熔沸点低,而食盐是离子化合物,离子间通过离子键结合,离子键是一种强烈的相互作用,断裂消耗很多的能量,所以熔沸点较高。因此乙醇中溶解微量食盐,用蒸馏方法分离。正确。

阅读理解

阅读理解

     Customs are social habits. They have been handed down through generations  among groups, social

classes, etc. Customs can be described as ways of doing things. They are particularly strong in social

practices on the occasions  of births, marriages and deaths.

     In China, these days, some people in cities are learning from Western customs. For example, some

brides dress in the long white dress that is usual bridal wear in many Western countries.

     Every people has special customs for New Year. The Han people have many interesting Spring

Festival customs. And now, quite a number of people living in the cities have followed the Western

customs of sending New Year greeting cards for January 1st.

     One interesting custom in China is that mothers wrap up their babies tightly.This is not the custom in

Western countries, where babies are usually dressed in loose garments.

1. Which of the following statement is right?

A. Customs have been formed during a short time

B. Customs have been formed little by little

C. Customs have been quickly formed and changed

D. Customs have never been changed

2. In this passage, the word "people" is      .

A. 人们      

B. 人类      

C. 民族      

D. 大家

3. How do the Chinese young people learn from Western countries at their marriages?

A. The brides(新娘)have on the white clothes.

B. Men wear the white coats.

C. Their parents all have attended their marriages.

D. Their marriages are only held in Church.

4. From this passage we know      .

A. the people all over China spend New Year in the same way

B. people in the villages and cities send New Year greeting ny e-mail each other

C. each people has his special custom for New Year

D. most of Chinese people like to spend Spring Festival.

5. The difference about clothing between Chinese and Western babies is that      .

A. Chinese babies are usually dressed in new clothes

B. Western mothers are used to dressing their babies in colourful clothes

C. Western babies are dressed in bigger clothes while Chinese babies are usually wrapped

D. Chinese babies have more clothes than Western babies

单项选择题