问题 选择题

图甲中电极均为石墨电极,下列叙述中正确的是

A.电子沿a→d→c→d路径流动

B.b极的电极反应为O2+4e+4H=2H2O

C.通电初期乙中的总反应为Cu+H2SO4 CuSO4+H2

D.反应过程中,甲、乙装置中溶液的pH都逐渐减小

答案

答案:C

电子可以沿着导线流动,在电解质溶液中是阴阳离子的移动产生电流,即电子沿a→d、c→b路径流动;电池电解质为NaOH,所以b电极的电极反应为O2+4e+2H2O=4OH;反应过程中,甲装置中产生水,所以溶液的pH减小,但是乙装置中由于H被消耗,所以pH增大。

改错题

短文改错。

There have be a lot of changes since World                                        1._____

WarⅡ. But perhaps a biggest change is                                              2._____

the telephone. People no longer write

letters for one another. They pick up the                                             3._____

telephone. Every house has at least two,

sometimes three, four and five telephones.                                          4._____

 Every office has many telephones. There

have more telephones than people in                                                   5._____

American. My little house has three                                                    6._____

phones. In the morning the first thing

which wakes me is my telephone ring.                                                7._____

Long distance telephone call are very                                                 8._____

cheap before seven o'clock in the morning.

So that my friend in Boston telephones me                                           9._____

to say “Good morning.” If you never have

 to write a letter, you simple take up the                                              10._____

telephone and say what you want to say.

问答题