问题 选择题

对图所示分子的描述不正确的是      (    )

A.该物质的分子式为

B.该物质所有氢原子不可能在同一平面上

C.该物质属于烷烃

D.该物质的一氯代物有3种

答案

答案:C

题目分析:由于分子中含有饱和的碳原子,且苯环是平面型结构,所以该物质所有氢原子不可能在同一平面上;分子中含有苯环,因此不属于烷烃,C不正确;根据有机物的结构简式可判断,分子中的氢原子分为3类,则该物质的一氯代物有3种,答案选C。

点评:共平面的题是近年来常考点,这类题切入点是平面型结构。有平面型结构的分子在中学主要有乙烯、1,3-丁二烯、苯三种,其中乙烯平面有6个原子共平面,1,3-丁二烯型的是10个原子共平面,苯平面有12个原子共平面,学生需要熟练掌握这些物质的结构。

阅读理解

From the beginning rivers have played an important in the life of man.Man of the earliest times used the rivers as a means of travel.Today rivers still serve as a great waterway for the transport and people.

In ancient times, man settled near rivers or on river banks and built up large empires.

Water is nature’s most valuable gift to man.Man needs water to irrigate his crops, to cook and to wash.In nations all over the world, rivers mean life and wealth.They feed and clothe the nations around them.

Water is also a source of energy and power.Man build huge dams across the rivers to control the water for irrigation and get the energy needed to drive generators.The electrical power is then directed to homes, cities, factories and television stations.

Man uses water each day.In a small way rivers help to keep man in good health and provide for his amusements.Various forms of water sports keep man strong and healthy.

小题1:Rivers have been important to man _______.

A.since they came into being

B.since the last century

C.since a few hundred years ago.

D.since the beginning of BC小题2:Man in old times traveled from one continent to another ______.

A.by air

B.by sea

C.by train

D.by bus小题3:Generators are machines that are used ______.

A.to direct electrical power

B.to control the water

C.to produce electricit

D.to build dams y小题4:Which of the following statements is true?

A.People get energy by building bridges across rivers.

B.In ancient times large empires grew up near dams.

C.People can be provided with amusements in small rivers.

D.Large rivers are still useful for transportation in modern times.

单项选择题