问题 实验题

为探究CO2和NaOH确实发生了化学反应,某实验小组的同学设计出了下列4种实验装置,请回答下列问题:                               

     

 (1)        (2)                  (3)                         (4)

(1)选择任意一种实验装置,简述出现的实验现象,解释产生该实验现象的原因:选择的实验装置是                  。实验现象为                         。产生该实验现象的原因是                                        

(2)某同学质疑上述实验设计,该同学质疑的依据是                            

(3)在原实验的基础上,请你设计实验证明CO2和NaOH肯定发生了化学反应。

答案

(1)装置(1);试管内液面上升;烧杯内液面下降二氧化碳与氧氧化钠溶液反应,使试管内气体压强减小,液体被压入试管中(或装置(2);软塑料瓶变瘪;二氧化碳与氢氧化钠溶液反应,使塑料瓶内压强减小,大气压将软塑料瓶压瘪了或装置(3);气球胀大;二氧化碳与氢氧化钠溶液反应,使锥形瓶内气体减少,大气压使气球胀大或装置(4);烧杯内的水流入锥形瓶中二氧化碳与氢氧化钠溶液反应,使锥形瓶内气体压强减小,大气压将液体压入锥形瓶)

(2)二氧化碳可能溶解于水,使气体的量减少也可以出现类似的现象;

(3)往二氧化碳与氢氧化钠溶液作用后的液体中加入过量的稀盐酸,如果有无色无味的气体产生,说明二氧化碳与氢氧化钠溶液已经发生了化学反应

单项选择题
完形填空
完形填空
     When I first came to the USA, I made friends with a neighbor who used to live only two blocks away
from my street. This friend taught me a lot about American __1__, but in some __2__I had to learn the
hard way, because we didn't have enough time together for me to learn all about American customs from
him.
     One day this same friend invited me to a party. It wasn't a (n)__3__party, only some kind of informal
gettogether. Since it was summer time he had a cookout where most of his American friends and relatives
were known to me, but there were others I had never met before.
     It was the most __4__party for me when I noticed that. Everybody was wearing jeans and simple
Tshirts for the day,__5__I arrived in proper dress with my shoes and my hair all fixed for a fancy party.
It was hard to __6__my embarrassment to the other guests. When one of them turned around and said,
"What nice clothes! What's the occasion?" I felt my __7__ burning hot. I didn't answer at all. If she knew
how bad I already felt, she wouldn't have come near me. But she did. Maybe she didn't ask __8__to
make me feel bad or uncomfortable, but my reaction had to do with the way I already felt.I could have
told her I had to go to another party afterward, but I did not want to continue the __9__.
     Many times I thought of going home and __10__but I knew they would notice. It would be even
__11__for me because I knew they would quickly think that I felt out of __12__. So I wanted to pretend
that I was OK.
     I have already realized their customs are different from mine, but after I talked to my friend, I was
more convinced that people here are more __13__. They care less about formality __14__it is a special
occasion, like a __15__or a very formal invitation.
( )1. A. art    
( )2. A. ways        
( )3. A. real        
( )4. A. exciting    
( )5. A. as          
( )6. A. explain      
( )7. A. heart        
( )8. A. carefully    
( )9. A. conversation
( )10. A. changing    
( )11. A. worse      
( )12. A. order      
( )13. A. indifferent
( )14. A. unless      
( )15. A. party      
B. culture      
B. conditions    
B. pleasant      
B. surprising    
B. while        
B. talk          
B. body          
B. intentionally
B. speech        
B. crying        
B. luckier      
B. breath        
B. casual        
B. if            
B. picnic        
C. history      
C. cases        
C. usual        
C. embarrassing  
C. when          
C. speak        
C. face          
C. willingly    
C. meeting      
C. sleeping      
C. better        
C. place        
C. open          
C. as long as    
C. meeting      
D. people    
D. methods    
D. evening    
D. enjoyable  
D. and        
D. say        
D. hand      
D. eagerly    
D. discussion
D. dancing    
D. easier    
D. mind      
D. careless  
D. since      
D. wedding