问题 选择题

下图是某化学反应的微观模拟示意图,下列说法错误的是

A.反应前后原子种类、数目均不变

B.该反应是置换反应

C.该反应的化学方程式为CH4 + 2O2CO2+2H2O

D.该反应中,反应物的质量比是1:2

答案

BD

题目分析:由题中化学反应的微观示意图可知:

化学反应前后原子种类、数目均不变;

这是一种单质和一种化合物反应,生成两种化合物的反应,不属于置换反应;

该反应的化学方程式为CH4 + 2O2CO2+2H2O;

该反应中,反应物的质量比,即CH4: O2=16:64=1:4。

选BD。

点评:化学反应都遵守质量守恒定律,反应前后,原子的种类、数量、质量都不变;

一种单质和一种化合物反应,生成另外一种单质和另一种化合物的反应是置换反应。

阅读理解

阅读短文,判断正误(正确的写T,错误的写F)。

    

     Imagine the year is 1666 and we can see a student called Isaac Newton. He's away from his university

for a holiday and at home with his family. Isaac Newton continues to study at home. He enjoys physics and

thinking about the mysteries of the world. 

     On a day when there is rain and sun at the same time he sees a beautiful rainbow in the sky. It has many

different colours, he is told that there are five. Newton wants to have his own rainbow because he wants to

look at it closely. He decides to do an experiment. On a sunny day he goes inside a small room and he makes

the room very dark. Then he makes a small hole and the sun comes inside, it's a small ray of light. It's white.

Newton takes a prism (棱镜) and holds it up to the light. The ray of light goes through the prism, but it isn't

white now there are many colours. The prism has split up (分解) the white light into different colours: Newton

has a rainbow.

     Newton looks at his rainbow carefully. He can see more than five colours, he can see seven. He says the

colours are: red, orange, yellow, green, blue, indigo and violet.

     But Newton is a scientist and he's always very interested in how things work. He has his rainbow but he

wants to know more. So he takes another prism and holds it up to the rainbow. The rainbow goes through the

second prism, but it isn't colourful now-it's white again. The prism has joined up the colours back into white

light. Newton is the first person to understand that light is a combination of all the rainbow colours together. 

     Newton also understands how we can see colour. Imagine a leaf in the sunshine. All the rainbow colours

fall on the leaf but it absorbs (吸收) all these colours. The only colour that is reflected (反射) is green, so the

leaf looks green. Different objects reflect different colours. And perhaps Newton's favourite fruit is an

orange-but what came first, the name of the fruit or the name of the colour?

( )1. In 1666 Isaac Newton was a university student learningphysics.                           

( )2. Newton was told that there were five colours in a rainbow and he believed it.            

( )3. Newton used a prism to split up the white light from the sun.                            

( )4. Newton understood that light was a combination (复合) of all the rainbow colours together.

( )5. Different objects reflect the same colours.                                              

单项选择题