问题 选择题

下列反应或过程属于吸热的是

A.盐酸与NaOH溶液的反应

B.H + H= H2

C.Al和Fe2O3的铝热反应

D.Ba(OH)2.8H2O与NH4Cl反应

答案

答案:D

根据常见的放热反应有:所有的物质燃烧、所有金属与酸反应、金属与水反应,所有中和反应,绝大多数化合反应和铝热反应;常见的吸热反应有:绝大数分解反应,个别的化合反应(如C和CO2),少数分解置换以及某些复分解(如铵盐和强碱),以及Ba(OH)2.8H2O与NH4Cl之间的反应.

A、盐酸与氢氧化钠溶液是中和反应,是常见放热反应,在反应中放出热量,故A错误;

B、B、新化学键的形成过程需要放出热量,故B错误;

C、C、Al和Fe2O3的铝热反应属于放热过程,故C错误;

D、D、Ba(OH)2.8H2O与NH4Cl之间的反应是吸热反应,故都正确.

E、故选D.

点评:本题考查化学反应的热量变化,学生应注重归纳中学化学中常见的吸热或放热的反应,对于特殊过程中的热量变化的要熟练记忆来解答此类习题.

阅读理解

任务型阅读。阅读短文,并根据短文内容回答问题。

  Why is more and more land becoming deserts?

  Scientists are trying to make the deserts into good land again. They want to

bring water to the deserts, so people can live and grow food there. They are

learning a lot about the deserts. But more and more of the earth are becoming

deserts all the time. Scientists may not be able to change the deserts in time.

  Scientists think that people make deserts. People are doing bad things to the

earth. (1)Some places on the earth do not get very much rain. But they still do

not become deserts. This is because some green plants are growing there. Small

green plants and grass are very important to dry places. Plants do not let the hot

sun make the earth even drier. Plants do not let the wind blow the soil away.

(2)When a little bit of rain falls, the plants hold the water. Without plants, the

land can become a desert much more easily.

根据短文内容,把划线部分译成汉语。

1.                                                                            

2.                                                                            

根据短文内容,回答下列问题。

3. Does the writer think scientists can turn the deserts into land? Why?

                                                                              

                                                                              

4. Why is more and more land becoming deserts while scientists are trying to

make the deserts into good land?

                                                                              

5. Why are small green plants and grass important to dry places?

                                                                              

单项选择题 A型题