问题 选择题

根据物质结构和元素周期表进行分析判断,下列叙述不正确的是(   )

A.第15列元素的最高价氧化物为R2O5

B.第三周期元素的离子半径,从左到右逐渐减小

C.同周期第ⅡA族与第IIIA族的元素原子序数之差可能为1或11或25

D.只含有非金属元素的化合物不一定是共价化合物

答案

答案:B

题目分析:第15列元素是第ⅤA族元素,最高价是+5价,所以最高价氧化物为R2O5,A正确;第三周期元素的金属阳离子离子半径小于非金属元素的阴离子半径,即选项B不正确;由于从第四周期开始第ⅡA族与第IIIA族中间相隔副族和第Ⅷ族,因此选项C正确;D正确,例如氯化铝是共价化合物,答案选B。

点评:该题是高考中的常见题型,属于中等难度的试题。主要是考查学生对周期表和元素周期律的熟悉了解程度,特别是灵活运用元素周期律解决实际问题的能力,有利于培养学生的逻辑推理能力,提高学生的应试能力和灵活应变能力。

阅读理解

阅读短文,选择正确答案。

      Now cities are full of cars. Some families even have two or more cars. Parking is a great problem, and so

is the traffic in the cities. Something will have to be done to change it.

      What will the cars of tomorrow be like?

      Little car may some day take the place of today's big cars. If everyone drives little cars in the future, there

will be less pollution in the air. There will also be more space for parking cars in cities, and the streets will be

less crowded. Three little cars can fit in the space now needed for one car of the usual size. 

     The little cars will cost much less to own and to drive. Driving will be safe, too. What is more, these little

cars can run about 65 kilometers per hour.

      Little cars of the future will be fine for getting around a city, but they will not be useful for long trips. If big

cars are still used along with the small ones, two sets of roads will be needed in the future. Some roads will be

used for the big, fast cars and other roads will be needed for the slower, smaller ones.

1. _______ is the big problem for those people who have cars. [ ]

A. Money

B. Parking

C. Driver

D. Waiting

2. Little cars in the futufe will bring _______ pollution in the air. [ ]

A. more

B. much

C. less

D. no

3. The little car's size may be _______ today's car's size. [ ]

A. one third of

B. two thirds of

C. as big as

D. as small as

4. People can _______ money with using the little cars. [ ]

A. spent

B. cost

C. take

D. save

5. The big cars are _______ the little cars for long trips. [ ]

A. as useful as

B. not so useful as

C. more useful than

D. less useful than

多项选择题