问题 选择题

在25℃时,分别用pH=9、pH=10的两种氨水中和同浓度、同体积的盐酸,消耗氨水的体积分别为V1和V2,则V1和V2的关系是(  )

A.V1=10V2

B.V1>10V2

C.V1<10V2

D.V2>10V1

答案

pH=9的氨水中c(OH-)=10-5 mol/L,pH=10的溶液中c(OH-)=10-4 mol/L,根据题意知,C1(NH3.H2O)V1=C2(NH3.H2O)V2,弱电解质溶液中,溶液浓度越大弱电解质电离程度越小,所以

V1
V2
=
c2
c1
>10,

所以得V1>10V2,故选B.

阅读理解

阅读理解

     Before you go to another country it is a great help if you know the language and some of the customs

of the country.

     When people meet each other for the rest time in Britain, they say, "How do you do?" and shake

hands. Usually they do not shake hands after they haven't met for a long time or when they will be away

from each other for a long time.

     Last year a group of German students went to England for a holiday. Their teacher told them that the

English people hardly shake hands, So when they met their English friends at the station, they kept their

hands behind their backs. The English students had learned that Germans shake hands as often as possible. So they put their hands in front and got ready to shake hands with them. It made all of them laugh.

1. If you are going to a foreign country, it is____ if you know the language and the customs of the country.

A. not useful

B. not helpful

C. very helpful

D. very sad

2. The English people usually shake hands when they ________.

A. meet every time

B. meet for the first time

C. say goodbye to each other

D. say hello to each other

3. Usually the English people don't shake hands________ .

A. when they won't be away for a long time

B. when they say "How do you do?"

C. when they just meet or say goodbye

D. after they haven't met for a long time

4. Which is RIGHT?

A. Germans shake hands as often as possible.

B. English people like shaking hands very much.

C. Germans hardly shake hands.

D. Neither the English people nor the Germans like shaking hands.

5. This story is about________ .

A. shaking hands

B. languages

C. customs

D. languages and customs

选择题