问题 填空题

在一定温度下向不同电解质溶液中加入新物质时溶液的导电性能发生变化,下图所示是其电流(I)随新物质加入量(m)的变化曲线。

以上4个导电性实验,其中与A图变化趋势一致的是__________,与B图变化趋势一致的是__________,与C图变化趋势一致的是__________。

①Ba(OH)2溶液中滴入H2SO4溶液至过量    ②醋酸溶液中滴入NH3·H2O至过量

③澄清石灰水中通入CO2至过量          ④NH4Cl溶液中逐渐加入适量NaOH固体

答案

②      ,    ①③    ,    ④

图像A中导电性先增大后减小,醋酸是弱电解质,加入氨水,生成强电解质醋酸铵,导电性增强,所以符合A的是②;图像B中导电性先减小,然后增大。反应①中生成硫酸钡和水,导电性降低,当硫酸过量时在增大。反应③中先生成碳酸钙和水,导电性降低,CO2过量时又生成碳酸氢钙,导电性增强,所以符合图像B的是①③;图像C中导电性是不变的,反应④中生成氨水和氯化钠,离子的浓度几乎是不变的,导电性不变,所以符合图像C的是④。

阅读理解

Dear Alice,

You really have two difficult questions here, so we’ll discuss them one at a time. Your problems at school may be a result of a number of things. You don’t say much about how these classmates get along with each other. It’s possible that all the students are feeling a little cautions(谨慎) in the first term.

It’s also possible that the others are unkind. If this is so, you have to find out why you are the class “outsider”.

In your letter you often offer to help others with their work. Is it possible that your classmates didn’t understand your offers? Could it seem that you were trying to “buy” friends with these offers?

Is it possible that you took no notice of your classmates when you had your good friends near you? They may have left hurt at that time. It may take a time for them to believe in you. If so, try to ask one classmate directly what the problem is. If you hear a negative(负面的) answer,at least you’ll know what to do.

Yours,

Shelia          

小题1:From the leter we know that Alice was very        .

A. lucky  B. unkind  C.unhappy

小题2:From the letter we can conclude() that        .

A. Alice wasn’t pleased with her teachers

B. Alice’s parents made her study too hard

C. Alice didn’t get along well with her classmates

小题3:In the letter Shelia talked about       possible reasons for Alice’s problems.

A. four  B. six  C. eight

小题4:Which of the following is NOT true according to the letter?

A. Alice felt her classmates weren’t kind to her.

B. Alice was very warm-hearted to help her classmates.

C. Alice didn’t want to get along well with her classmates.

小题5:Shelia’s advice to Alice is that      .

A. Alice should find out the true reason for her problems

B. Alice should leave school as soon as possible

C. Alice should get one negative answer

问答题