问题 问答题

已知:铝跟盐酸或氢氧化钠溶液都能发生反应生成氢气.反应的化学方程式分别为:

2Al+6HCl=2AlCl3+3H2↑         2Al+2NaOH+2H2O=2NaAlO2+3H2

(1)若要制取3g氢气,需要多少gAl与足量的稀盐酸反应?

(2)相同条件下,等质量的铝分别跟足量的稀盐酸、NaOH溶液反应,放出氢气的质量______(填序号).

A.铝跟稀盐酸反应放出的氢气多

B.铝跟氢氧化钠溶液反应放出的氢气多

C.一样多

D.不能判断

答案

(1)设需要Al的质量为x

2Al+6HCl=2AlCl3+3H2

54               6

x               3g

∴54:6=x:3g

解之得:x=27g

答:需要Al的质量为27g.

(2)由反应的化学方程式可以得知,相同条件下,等质量的铝分别跟足量的稀盐酸、NaOH溶液反应,放出氢气的质量都是3H2,因此,放出氢气的质量一样多.

故选C.

阅读理解

Look at the center circles of Diagram (图) A and Diagram B.  Which of the centre circles looks larger? 

Take a first look and you probably think that the centre circle in Diagram A is smaller than that in Diagram B. In fact , they are exactly the same size.

Then look at the picture on the right. What do you see? A vase ? Or two faces? Does the picture change quickly from one to the other again and again? Maybe or maybe not, but you can never see them at the same time. 

"What's happening? Is something wrong with my eyes?" You may wonder at what you see. Don't worry. Here is how it goes:

When we look at things, our eyes send messages to our brains and then our brains interpret (解读) the information. However, sometimes our brains interpret the received information in a wrong way. It seems that our eyes are playing a joke on us. This often happens and we call it "Visual illusion" (视觉错误). 

Movie makers often make use of illusions. They make the objects around actors much smaller or bigger than usual. This makes us believe that the actors are much larger or smaller than they usually are. The movies Jurassic Park and Honey I shrunk the kids just make use of illusions.

小题1:The centre circle in Diagram A looks smaller than that in Diagram B. That's because           .

A. something is wrong with our eyes

B. the two circles are not the same size

C. our brains interpret the information in a wrong way

D. the two pictures change quickly from one to the other

小题2:What's the right order according to the passage?

a. We look at things with our eyes.              b. Our brains interpret the messages.

c. Our brains tell us what we have seen.      d. Our eyes send messages to our brains.

A.adbc

B.cabd

C.acdb

D.bcad小题3:Movie makers make use of visual illusions to            .

A.help the actors look better

B.make the actors much braver

C.help the actors become stronger

D.make the actors seem different in size小题4:In the picture on the right, it seems that Line AB is shorter than Line CD, but in fact Line AB is as long as Line CD. Which paragraph can explain what has happened to our eyes?___________

   

A.The second one.

B.The third one.

C.The fifth one.

D.The sixth one.

小题5:The text is probably taken from            .

A.an advertisement

B.a science book

C.a movie magazine

D.a story book

单项选择题