问题 填空题

按要求完成下列各题:

(1)现有H、C、O、Ca、Fe五种元素,选择其中一种或几种元素组成符合下列要求的物质,并用化学式填空:分子量最小的氧化物___________;制二氧化碳的石灰石的主要成分___________.

(2)高铁酸钾(K2FeO4)是一种“绿色”环保高效净水剂,可由如下反应制得:Fe2O3+3X+4KOH=2K2FeO4+3KNO2+2H2O,则X的化学式为___________,K2FeO4中Fe的化合价为___________价.

答案

(1)H2O;CaCO3;(2)KNO3;+6.

题目分析:(1)分子量最小的氧化物是水,其化学式为:H2O.制二氧化碳的石灰石的主要成分是碳酸钙,其化学式为:CaCO3

(2)根据反应的化学方程式Fe2O3+3X+4KOH=2K2FeO4+3KNO2+2H2O,反应物中铁、氧、钾、氢原子个数分别为2、7、4、4,反应后的生成物中铁、氧、钾、氮、氢原子个数分别为2、16、7、3、4,根据反应前后原子种类、数目不变,则3X中含有3个钾原子、3个氮原子和9个氧原子,则每个X分子由1个钾原子、1个氮原子和3个氧原子构成,则物质X的化学式为KNO3

钾元素显+1价,氧元素显﹣2价,设铁元素的化合价是x,根据在化合物中正负化合价代数和为零,可得:(+1)×2+x+(﹣2)×4=0,则x=+6价.

判断题
阅读理解

It is natural for young people to be critical of their parents at times and to blame them for most of the misunderstandings between them. They have always complained, more or less justly, that their parents are out of touch with modern ways; that they are possessive and dominant; that they do not trust their children to deal with problems; that they talk too much about certain problems—and that they have no sense of humor, at least in parent—child relationships. I think it is true that parents often underestimate their teenage children and also forget how they themselves felt when young.

Young people often make their parents angry at their choices in clothes and hairstyles, in entertainers and music. This is not their motive. They feel cut off from the adult world into which they have not yet been accepted. So they create a culture and society of their own. Then, if it turns out that their music or entertainers or vocabulary or clothes or hairstyles make their parents angry, this gives them extra enjoyment. They feel they are superior, at least in a small way, and that they are leaders in style and taste.    

Sometimes you are resistant, and proud because you do not want your parents to agree what you do. If they agree, it looks as if you are betraying your own age group. But in that case, you are supposing that you are the underdog; you cannot win but at least you keep your honor. This is a passive way of looking at things. It is natural enough after long years of childhood, when you were completely under your parents' contro1. But it ignores the fact that you are now beginning to be responsible for yourself. If you plan to control your life, cooperation can be part of that plan. You can attract others, especially your parents, into doing things the way you want. You can impress others with your sense of responsibility, so that they will let you choose what you want to do.  

小题1:The first paragraph is mainly about_________.

A.the teenagers' criticism of their parents

B.misunderstandings between teenagers and their parents

C.the control of the parents over their children

D.the teenagers' ability to deal will problems小题2:Teenagers tend to have strange clothes and hairstyles mainly because they________.

A.want to show their existence by creating a culture of their own

B.have a strong desire to be leaders in style and taste

C.have no other way to enjoy themselves better

D.want to make their Parents angry小题3:Teenagers do not want their parents to agree whatever they do because they_______.

A.have already been accepted into the adult world

B.feel that they are superior to the adults

C.are not likely to win over the adults

D.have a desire to be independent小题4:To improve parent—child relationships,teenagers are advised to be_________.

A.attractive

B.positive

C.cooperative

D.productive