问题 选择题

某温度下在,密闭容器中发生如下可逆反应:2M(g)+N(g) 2E(g),若开始时只充入2 mol E(g),达平衡时,E的转化率为40%;若开始时充入2 mol M和1 mol N的混合气体,达平衡时混合气体的压强比起始时减少了

A.20%

B.40%

C.60%

D.80%

答案

答案:A

   2M(g)+N(g) 2E(g)

起始物质的量 0      0          2

转化物质的量 2x     x          2x

平衡物质的量2x      x         2-2x

达平衡时,E的转化率为40%,2x/2=40%   x=0.4

若开始时充入2 mol M和1 mol N,达平衡时和第一次是全等等效平衡,平衡时M、N、E的物质的量分别为0.8mol、0.4mol、1.2mol,平衡时总物质的量为2.4mol,混合前是3mol,达平衡时混合气体的压强比起始时减少了(3-2.4)/3=20% ,故选A

阅读理解

阅读理解

       Henry works in a factory. He comes from a poor family and was in school for only four years. He

has to do the hard work, but he is paid less. He likes to watch football matches very much and spends

much time on them.

       One afternoon there was a big football match on the playground. He borrowed some money from

his friend and hurried there. There were a lot of people there. And all the tickets were sold out. He was

sorry for it. He saw a pole outside the playground and climbed it quickly. A policeman came and said,

"It is dangerous to stay on it! Come down!"

       " Wait a minute, please!" Henry said and just at that moment the policeman heard cheers on the

playground and asked in a hurry, " which team has kicked a goal?" " ours!" " wonderful! You can stay

there. But take care!"  The policeman said happily and left. When the match would be soon over, he

came back again and asked, " who has won?" " Theirs, 3:2 " " Come down," the policeman said angrily. " Such a match is not worth watching!"

       Henry had to come down. But soon they heard cheers again. The policeman said in a hurry, " Climb

up quickly and see who has kicked a goal."

1. From the passage we know that _________.

A. Henry doesn't like his work              

B. Henry comes from a rich family.

C. Henry doesn't like the policeman          

D. Henry is paid less.

2. Henry failed to get a ticket for the match that day because ___________.

A. he had no money to buy a ticket            

B. he didn't want to buy a ticket

C. he had no time to buy a ticket              

D. all the tickets were sold out

3. The policeman asked Henry to come down the pole at first because ____________.

A. it was dangerous                        

B. Henry had no ticket

C. their team kicked a goal                  

D. the other team kicked a goal

4. From the third paragraph, we can guess that _____________.

A. the policeman wanted to teach Henry a lesson.

B. the policeman tried to please Henry

C. the policeman didn't like Henry.

D. the policeman was also a football fan.

5. The policeman asked Henry to climb up the pole ____________

A. to cheer for their team                    

B. to see the result of the match

C. to cheer for the other team                 

D. to say goodbye to their team

单项选择题 共用题干题