问题 选择题

用NA表示阿伏加德罗常数,下列叙述正确的是

A.标准状况下,22.4L H2含有的分子数为NA

B.18g H2O在标准状况下的体积是22.4L

C.常温常压下,1.6g CH4含有的电子数为NA

D.物质的量浓度为0.5mol /L的MgCl2溶液中,含有Cl个数为 NA

答案

AC

题目分析:A:标准状况下,气体摩尔体积为22.4L/mol,所以22.4L H2含有的分子数为NA

;B:H2O没有标明状态,只有气体在标况下摩尔体积为22.4L/mol,固体和液体不是;C:CH4的摩尔质量为16g/mol,所以1.6g CH4的物质的量是0.1mol,即0.1NA个分子,一分子CH4含有10个电子,故C正确;D:只说物质的量浓度,并没有说明有多少MgCl2溶液,无法计算。

点评:本题考查学生有关阿伏伽德罗常熟的有关计算知识,可以根据所学知识来回答,难度不大.

阅读理解

根据短文内容,从短文后的选项中选出能填人空白处的最佳选项。选项中有两项为多余选项。

                                                                The Mississippi

     The Mississippi is a great river whose relationship with man goes way back beyond its discovery in the

16th century. The River Indians used it as a highway and as a source of food, and it was they who gave it

its name-"misi" meaning "great" and "sipi" meaning "water". When the length of its branch, the Missouri, is

added to it, the Mississippi becomes greater. 1_____. From the source of the Missouri to the tip of the delta

(三角洲), it is 2480 miles long.

     Great rivers are likely to suffer floods. In 1927 the Mississippi flooded 26 thousand acres, sweeping

away farms, towns, everything in its path. In 1938 its floods drowned or killed 200 people and made millions

homeless. Today the river has largely been controlled. 2_____.

     Industries have spread down some of the waterways of the delta, but otherwise the delta is a remote place,

the homeland of a little colony of French Canadians that the British drove out of Nova Scotia in the 18th

century. They still speak French, mixed with English, Indian, Spanish and Negro idioms. They keep to

themselves, farming the rich soil of the delta. 3_____. 

     4_____. Pioneers who first reached its banks wondered not only where it went, but what lay beyond. In

1764 the French founded a city on the right bank of the river, and named it after their king, Louis XV. This

city, named St. Louis, became the jumping-off place for the adventurous men and women who opened up

the Great Plains, and the way to the Far West.

     Some 40 years earlier, at the beginning of the 18th century, the French had founded another city just above

the Mississippi delta, New Orleans. 5_____. New Orleans is one of the great ports of the world, and one of

the greatest terminals for both sea and river traffic.

A. It was the Mississippi that made the city what it is

B. Levees, high banks built of earth, hold back the flood waters

C. Therefore, as we know, it's the third longest river in the world

D. It is known that the "Great Water" has also been a frontier river

E. However, they paddled up and down the Mississippi in their boats to seek their fortune

F. The "Great Water" always remains a thread, for the streets of the city are below the'level of the river

G. They call themselves Cajuns, who have actually been leading fairly primitive lives and preserving their own

     traditions

单项选择题