问题 填空题

有以下6个反应(反应条件略):

A.2Na+2H2O═2NaOH+H2↑     B.CH4+2O2═CO2+2H2O     C.KClO3═2KCl+3O2↑  D.CaCO3+2HCl═CaCl2+H2O+CO2

E..Na2O+CO2═Na2CO3                F.CO2+C═2CO

属于化合反应的有______(填编号,下同),属于分解反应的有______,属于复分解反应的有______,属于置换反应的有______,属于氧化还原反应的有______.

答案

A.2Na+2H2O═2NaOH+H2↑,反应物、生成物都是单质和化合物,且有化合价的变化,所以既属置换反应,又属氧化还原反应;

B.CH4+2O2═CO2+2H2O,该反应中有化合价的变化,所以属氧化还原反应;

C.KClO3═2KCl+3O2↑,反应物是一种,生成物是多种,且有化合价的变化,所以既属分解反应,又属氧化还原反应;

 D.CaCO3+2HCl═CaCl2+H2O+CO2↑,该反应的反应物相互交换离子生成新的化合物,所以属复分解反应;

E..Na2O+CO2═Na2CO3,反应物是多种,生成物是一种,且没有化合价的变化,所以属化合反应;

F.CO2+C═2CO,反应物是多种,生成物是一种,且有化合价的变化,所以既属化合反应又属氧化还原反应;

故答案为:EF;  C; D;  A;  ABCF.

多项选择题
单项选择题

阅读下面短文,掌握其大意,然后从21—40各题所给的四个选项(A、B、C和D)中,选出最佳选项,并在答题纸上将该选项标号涂黑。

During the war,my husband was stationed at an army camp in a desert in California.I went to live there in order to be 21  him. I hated the place .I had never  22  been so unhappy . My husband was ordered out on a long-term duty,and I was left in a tiny shack(棚屋) alone. The heat was  23  -almost 125 0F even in the shade of a cactus(仙人掌)。 24  a soul to talk to . The wind blew non-stop ,and all the food I ate ,and the evry air I breathed,were  25   with sand , sand , sand !

I was so sorry for myself that I wrote to my parents. I told them I was  26   and coming back home.I said I couldn’t stand it one minute longer. I  27  be in prison! My father answered my  28  with just two lines-two lines that will always sing in my  29  - two lines that completely changed my life :

Two men looked out from prison bars

One saw the mud ,the other saw the stars

I read those two lines  30   I was ashamed of myself. I made up my mind I would find out what was good in my present  31  ; I would look for the stars

I made friends with the natives,and their  32  amazed me. They gave me presents of their favorite artworks which they had  33  to sell to toueists . I studied the delightful forms of the cactus .I watched for the desert sunsets,and  34  for seashells that had been left there millions of years ago when the desert had been an ocean  35 

What brought about this  36   change in me ? The desert hadn’t changed , 37   I had .I had changed my  38   And by doing so ,I changed an unhappy experience into the most amazing  39  of my life . I was excited by this new world that I had dicovered I had looked out of my self-creatded prison and  40   the stars

22()

A.before

B.already

C.then

D.still