问题 推断题

有一包白色固体粉末,可能含有CuSO4、Na2SO4、(NH4)2CO3、BaCl2、NH4Cl、KCl中的一种或几种。现做如下实验:

根据上述实验现象判断:

(1)白色固体中一定不含           ,一定含有           ,可能含有           

(2)写出①中化学反应方程式:                                 

(3)写出②中化学反应方程式:                                 

答案

(1)CuSO4、(NH4)2CO3      Na2SO4、BaCl2、NH4Cl        KCl

(2)Na2SO4+BaCl2=BaSO4↓+2NaCl

(3)NaOH+NH4ClNaCl+NH3↑+H2O

题目分析:(1)由步骤①可知,白色固体中一定没有硫酸铜,因为硫酸铜溶于水呈蓝色;过滤得到的白色固体加入足量的盐酸不溶解,因此白色固体中一定有硫酸钡,原物质中一定有了氯化钡和硫酸钠,就一定不能再有碳酸铵了,因为碳酸钡溶于盐酸,此白色固体是硫酸钡,说明原混合物中一定有Na2SO4、BaCl2;由步骤②可知,加入氢氧化钠溶液加热,产生了能使湿润的红色石蕊试纸变蓝的气体,此气体是氨气,因此原白色固体中一定含有氯化铵;KCl可能有也可能没有;故答案为:CuSO4、(NH42CO3;  Na2SO4、BaCl2、NH4Cl;  KCl   

(2)硫酸钠和氯化钡反应生成硫酸钡白色沉淀和氯化钠,配平即可,故答案为:Na2SO4+BaCl2=BaSO4↓+2NaCl

(3)氢氧化钠和氯化铵在加热的条件下反应生成氯化钠和水和二氧化碳,故答案为:NaOH+NH4ClNaCl+NH3↑+H2O

选择题
阅读理解

阅读理解。

     How is it that siblings (兄弟姐妹) can turn out so differently? One answer is that in fact each sibling

grows up in a different family. The firstborn is, for a while, an only child, and therefore has a completely

different experience of the parents than those born later. The next child is, for a while, the youngest, until

the situation is changed by a new arrival. The mother and father themselves are changing and growing up

too. One sibling might live in a stable and close family in the first few years; another might be raised in a

family crisis, with a disappointed mother or an angry father.

     Sibling competition was identified as an important shaping force as early as in 1918. But more recently, researchers have found many ways in which brothers and sisters are a lasting force in each others' lives.

Dr. Annette Henderson says firstborn children pick up vocabulary more quickly than their siblings. The

reason for this might be that the later children aren't getting the same one-on-one time with parents. But

that doesn't mean that the younger children have problems with language development. Later-borns don't

enjoy that much talking time with parents, but instead they harvest lessons from bigger brothers and sisters, learning entire phrases and getting an understanding of social concepts such as the difference between "I"

and "me".

      A Cambridge University study of 140 children found that siblings created a rich world of play that

helped them grow socially. Love-hate relationships were common among the children. Even those siblings who fought the most had just as much positive communication as the other sibling pairs.

     One way children seek more attention from parents is by making themselves different from their siblings, particularly if they are close in age. Researchers have found that the first two children in a family are

typically more different from each other than the second and third. Girls with brothers show their

differences to a maximum degree by being more feminine than girls with sisters. A 2003 research paper

studied adolescents from 185 families over two years, finding that those who changed to make themselves different from their siblings were successful in increasing the amount of warmth they gained from their

parents.

1. The underlined part "in a different family" (in Para. 1) means "_______".

A. in a different family environment

B. in a different family tradition

C. in different family crises

D. in different families

2. In terms of language development, later-borns ________.

A. get their parents' individual guidance

B. learn a lot from their elder siblings

C. experience a lot of difficulties

D. pick up words more quickly

3. What was found about fights among siblings?

A. Siblings hated fighting and loved playing.

B. Siblings in some families fought frequently. 

C. Sibling fights led to bad sibling relationships.

D. Siblings learned to get on together from fights.

4. The word "feminine" (in Para. 4) means "_______".

A. having qualities of parents  

B. having qualities of women

C. having defensive qualities

D. having extraordinary qualities