问题 选择题

人造地球卫星用到的一种高能电池——银锌蓄电池,其电极分别是Ag2O和Zn,电解液是KOH溶液。该电池的电极反应式为Zn+2OH--2e-=Zn(OH)2,Ag2O+H2O+2e-=2Ag+2OH-。下列说法中正确的是(    )

①锌为负极,Ag2O为正极;②放电时,正极附近溶液OH-浓度增大;③工作时电流由Ag2O极经外电路流向Zn极;④溶液中阴离子向正极方向移动,阳离子向负极方向移动

A.①

B.①②④

C.①②③

D.①②③④

答案

答案:C

题目分析:根据电池反应式Ag2O+Zn=2Ag+ZnO知,失电子的物质作负极,得电子的物质作正极,原电池放电时,电子从负极沿导线流向正极;根据电池电极附近氢离子或氢氧根离子浓度的变化判断溶液PH值的变化。

④溶液中阴离子向负极方向移动,阳离子向正极方向移动,故错。故选C。

故选C。

点评:本题考查了原电池原理,难度不大,明确原电池正负极的判断方法、外电路中电子的流向、电极附近离子浓度的变化导致溶液PH值的变化即可解答本题。

完形填空
完形填空。
     I think we should try to find a happy memory, something to lift us up on those unpleasant days.
     I`m saying this because I think I just found mine!
     I had some work in Glasgow then. I was on a really   1   schedule, which meant I would have no time
for myself all day. I was having one of those days, when the train was completely   2   and the conversation
going on around me seemed to be particularly   3  . Besides, I had a bit of a headache.   4   quickly across
the station hall, I fished some   5   from my pocket. There was usually someone at the exit   6   the Big
Issue (a magazine that helps homeless folk earn a living). 
       7   the crowd parted ways at the bottom of the hall, I saw someone selling the Big Issue. She really
looked like she`d been sleeping   8  . Her clothes were   9   and she obviously hadn`t had a scrub up (擦洗)
for quite a while.
     As I  10  the exit, I saw that she was   11   from side to side. At first I thought she was trying to keep
  12   against the biting wind. But she wasn`t. She was moving in time to a  13 . I couldn't hear her, but I
could see her lips moving.
      When I got closer, I saw a white  14  hanging from her elbow and noticed that she had sunken eyes.
She was  15 , dirty and living on streets. I came closer and through the  16   of the traffic I could hear her
  17  the immortal (不朽的) line,"…And I think to myself, what a wonderful world!".
     I bought her last magazine for twice what I'd originally  18  . She thanked me, and  19  her belongings
and went tapping off along the pavement -still singing! So, I have my happy  20  for the day, and I think it
will stay with me a long,long time.
( )1. A. enjoyable 
( )2. A. crowded  
( )3. A. moving   
( )4. A. looking  
( )5. A. cigarettes 
( )6. A. selling  
( )7. A. With     
( )8. A. comfortably
( )9. A. shabby   
( )10. A. left   
( )11. A. jumping  
( )12. A. active  
( )13. A. dance   
( )14. A. issue   
( )15. A. deaf   
( )16. A. noise   
( )17. A. recite  
( )18. A. expected
( )19. A. picked up
( )20. A. decision 

B. relaxing   
B. delayed   
B. interesting 
B. walking   
B. sweets     
B. buying     
B. Since     
B. rough     
B. casual     
B. passed     
B. limbing   
B. energetic 
B. tune      
B. arm      
B. lame      
B. music     
B. compose   
B. charged   
B. threw away  
B. memory     

C. tight   
C. loaded  
C. pleasing 
C. wandering 
C. change  
C. collecting
C. Until   
C. soundly  
C. tidy   
C. approached
C. rolling  
C. warm   
C. step   
C. stick   
C. mad    
C. voice   
C. read   
C. intended 
C. turned out
C. program  
D. tiring         
D. crashed        
D. meaningless    
D. searching      
D. paper          
D. delivering     
D. As             
D. anxiously      
D. fashionable    
D. examined       
D. rocking        
D. awake          
D. sound          
D. log            
D. blind          
D. sound          
D. sing           
D. organized      
D. hid away       
D. design         
单项选择题 B1型题