题目

下列关于ⅦA族元素的叙述正确的是 ( ) A.ⅦA族元素是同周期中原子半径最大的元素(稀有气体元素除外) B.ⅦA族元素是同周期中非金属性最弱的元素 C.ⅦA族元素的最高正价都是+7价 D.ⅦA族元素其简单阴离子的核外电子层数等于该元素所在的周期数 答案：选D。同周期元素自左向右,原子半径逐渐减小,非金属性逐渐增强,故ⅦA族元素是同周期中原子半径最小,非金属性最强的元素,A、B错;F无正价,C错;ⅦA族元素得电子形成简单阴离子时,其电子层数不变,D正确。 阅读理解 The word“day”has two meanings．When we talk about the number of days in a year, we are using“day”to mean 24 hours．But when we talk about day and night, we are using“day”to mean the time between sunrise and sunset．Since the earth looks like a ball, the sun can shine on only half of it at a time．Always one half of the earth is having day and the other half night．A place is moved from day into night and from night into day over and over by the spinning(旋转)of the earth．At the equator(赤道)day and night are sometimes the same length．They are each twelve hours long．The sun rises at 6 in the morning and sets at 6 in the evening．For six months the North Pole is tilted(倾斜)toward the sun．In those months the Northern Hemisphere(半球)gets more hours of sunlight than the Southern Hemisphere．Days are longer than nights．South of the equator nights are longer than days．For the other six months the North Pole is tilted away from the sun．Then the Southern Hemisphere gets more sunlight．Days are longer than night．North of the equator nights are longer than days．Winter is the season of long nights．Summer is the season of long days． (1) When the Western Hemisphere is having day, the Eastern Hemisphere is having ________． [　　] A． both day and night B． day C． neither day nor night D． night (2) A place is moved from day into night and from night into day over and over by ________ of the earth． [　　] A． the pushing B． the pulling C． the spinning D． the passing (3) At the equator day is as long as night ________． [　　] A． sometimes B． never C． usually D． always (4) When the North Pole is tilted toward the sun, the Northern Hemisphere gets ________ sunlight． [　　] A． less B． more C． all D． no (5) When it is winter in China, ________． [　　] A． the USA is tilted toward the sun B． the South Pole is tilted away from the sun C． the North Pole is tilted toward the sun D． the North Pole is tilted away from the sun