问题 选择题

下列说法正确的是

A.CH3CH2CH3分子内的三个碳原子在同一条直线上

B.CH2=CHCH3分子内的三个碳原子共平面

C.苯分子中所有原子共平面

D.CH4分子中所有原子共平面

答案

BC

题目分析:饱和碳原子的基本构型都是四面体,所以CH3CH2CH3分子内的三个碳原子不在同一条直线上,而是在同一个平面上,A不正确;碳碳双键是平面型结构,则丙烯分子中碳原子都是平面型结构,B正确;苯分子也是平面型结构,C正确;甲烷是正四面体型结构,D不正确,答案选BC。

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、苯等,其中乙烯平面有6个原子共平面,苯平面有12个原子共平面。这些分子结构中的氢原子位置即使被其他原子替代,替代的原子仍共平面。据此可以判断。

多项选择题
阅读理解

Building after building under water.Refugees in shelters.Thousands of others unsure where to go.Bodies in streets.This is what one of America's historic cities was reduced to this week by a powerful storm, Katrina(卡特里娜).The mayor of New Orleans says thousands may be dead.Hurricane Katrina also caused death and destruction in parts of Mississippi and Alabama along the Gulf of Mexico.

New Orleans is famous for its wild Mardi Gras celebrations.New Orleans is also a major port for foreign oil and other shipping trade.Yet the city of nearly five hundred thousand people was built below sea level.New Orleans has depended on levees to control floods from the Mississippi River.Katrina struck on Monday.New Orleans avoided a direct hit.But two of the levees failed the next day.Most of the city was flooded.Helicopters dropped huge sandbags to fill the breaks.But the water had no place to go.Pumping stations had no power.

America faces one of the worst natural events in its history.President Bush says the recovery will take years.People were told to leave the path of the storm.But some would not or could not.Many of those worst affected by Katrina are poor and black.African-American leaders and others were angry that government aid did not arrive faster.President Bush visited some of the damaged areas on Friday.He said the way officials reacted to the crisis was unacceptable.

小题1:Which is true of the following details about New Orleans?

A.New Orleans is a newly-built city of America

B.There were no black people in New Orleans.

C.This is the first time that hurricane has stricken it.

D.New Orleans is a major port for foreign oil and other shipping trade.小题2:What does the underlined word “levees”(in the second paragraph) mean?

A.trees

B.dams

C.ports

D.ships小题3:Which is right about the Hurricane Katrina?

A.It also caused the destruction in parts of Mississippi.

B.A lot of people died in this disaster.

C.It cut off the electricity supply of the city.

D.All of the above is right.小题4:What can we learn from the text?

A.President Bush was not concerned about this disaster.

B.The recovery of the city will take a few days.

C.In this disaster the government aid didn’t arrive in time.

D.In this city there were no pump stations.