问题 选择题

下列说法正确的是(  )

A.水蒸发过程中,水分子、氢原子和氧原子都没有改变,是物理变化;而电解水过程中.分子、氢原子和氧原子都发生了改变,是化学变化

B.一切物质都是由分子构成,而分子又是由原子构成,所以分子比原子大

C.气体易被压缩是因为构成气体的分子间有相对较大间隙,固体难被压缩,是因为构成固体的分子间间隙相对较小

D.二氧化碳(CO2)和一氧化碳(CO)都是由碳元素和氧元素组成的,所以两物质的化学性质相同

答案

A、水蒸发过程中,分子不变,而化学变化的过程中,水分子分成氢原子和氧原子,氢氧原子不再改变,故A错误;

B、构成物质的基本微粒有分子、原子和离子等,不是所有的物质都是由分子构成的,故B错误;

C、分子间有一定的间隔,物质能被压缩是因为分子间有间隔,气体物质分子间隔较大,易被压缩,而液体和固体物质分子间隔较小,故C正确;

D、二氧化碳和一氧化碳的组成元素相同但是分子构成不同,因此化学性质不同,故D错误;

故选C.

阅读理解

Johnny Smith was a good math student at a high school. He loved his computer. He came home early every day, then he worked with it till midnight. But Johnny was not a good English student, not good at all. He got an F in his English class. One day after school Johnny joined his computer to the computer in his high school office. The school office computer had the grades of all the students: the math grades, the science grades, the grades in arts and music, and the grades in English. He found his English grade. An F! Johnny changed his English grade from an F to A. Johnny' parents looked at his report card. They were very happy.

"An A in English!" said Johnny's Dad. "You're a very clever boy, Johnny."

Johnny is a hacker(黑客). Hackers know how to take information from other computers and put new information in. Using a modem(调制解调器), they join their computers to other computers secretly. School headmasters and teachers are worried about hackers. So are the police, for some people even take money from bank computer account(账户) and put it into their own ones. And they never have to leave home to do it! They are called hackers.

小题1:Johnny changed his English grade with the computer in _______.

A.the classroom

B.the school office

C.a bank near his house

D.his own house小题2:When Johnny's parents saw the report, they were happy because _______.

A.Johnny was good at math

B.Johnny loved computers

C.Johnny could join one computer to another

D.they thought Johnny was not poor in English any longer小题3:Who are worried about hackers in the story?   .

A.Johnny's parents.

B.School headmasters, teachers and the police.

C.The police.

D.School headmasters and teachers.小题4:What should the hackers know well, do you think, after you read this story?   .

A.Information.

B.Back computer accounts.

C.Computers.

D.Grades.小题5:The last paragraph is about _______.

A.Johnny

B.computers

C.hackers

D.modem

判断题