题干

X、Y、Z、W、M五种短周期元素,X、Y同周期,X、Z同主族,Y形成化合物种类最多,X2、W3+具有相同的电子层结构,M为短周期主族元素中原子半径最大的元素.下列说法正确的是(  )

A:原子半径大小顺序为W>X>Z>Y

B:W元素形成的可溶性盐溶液一定显酸性

C:M、X只能形成离子化合物,且形成的离子化合物中只含离子键

D:W的最高价氧化物与Z、M的最高价氧化物的水化物均能反应

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D

同类题1

某校生物探究性学习小组同学为探究某些生态因素在生态系统中的作用,设计了如下实验:

实验材料用具:有盖玻璃瓶,池水,河泥,水藻,小鱼等.

实验步骤:

第一步:在四个大小形状相同的有盖玻璃瓶中加入等量的池水,另外向C、D瓶中加入等量的河泥;

第二步:向B、C、D中放入等量的水藻;

第三步:向四个瓶中放入大小形状和生长状况相近的小鱼各两条;

第四步:把A、C、B瓶置于阳光下,D瓶放在黑暗的环境中.实验装置如下图所示:

第五步:观察记录实验现象.

实验结果:A~D 4个装置中小鱼存活时间的长短依次是C>B>A>D.

请你利用所学知识,帮助该小组同学分析并回答下列问题:

(1)实验装置A、B、C所模拟的生态系统中,相同的非生物因素是池水、____ 、温度、空气、空间等;

(2)小生态瓶B、C、D均可以看作是一个小生态系统.从生态系统的成分分析,在这些小生态系统中,池水和河泥中的细菌等微生物属于____ .

(3)比较A、B、C的实验结果可知,小鱼存活时间的长短与____ 和河泥有关.

(4)比较A、B的实验结果可知,水藻的作用是进行____ .

(5)D装置中,小鱼存活的时间比A装置中的存活时间短,最可能的原因是水藻呼吸作用消耗了____ .

(6)比较C、D的实验结果可说明,水藻在有____ 的条件下,才能释放氧气.

同类题5

根据短文理解,选择正确答案。

    When other nine-year-old kids were playing games, she was working at a petrol station. When other teens were studying or going out, she struggled to find a place to sleep on the street. But she overcame these terrible setbacks to win a highly competitive scholarship and gain entry to Harvard University. And her amazing story has inspired a movie, "Homeless to Harvard: The Liz Murray Story" shown in late April.

    Liz Murray, a 22.year-old American girl, has been writing a real-life story of willpower and determination. Liz grew up in the shadow of two drug-addicted parents. There was never enough food or warm clothes in the house. Liz was the only member of the family who had a job. Her mother had AIDS and died when Liz was just l5 years old. The effect of that LOSS became a turning point in her life. Connecting the environment in which she had grown up with how her mother had died,she decided to do something about it.

    Liz went back to school. She threw herself into her studies, never telling her teachers that she was homeless. At night, she lived on the streets. ".What drove me to live on had something to do with understanding, by understanding that there was a whole other way of being. I had only experienced a small part of the society,'' she wrote in her book Breaking Night.

    She admitted that she used envy to drive herself on. She used the benefits that come easily to others, such as a safe living environment, to encourage herself that "next to nothing could hold me down".

    She finished high school in just two years and won a full scholarship to study at Harvard University. But Liz decided to leave her top university a couple of months earlier this year in order to take care of her father, who has also developed AIDS."I love my parents so much. They are drug addicts. But I never forget that they love me all the time."

    Liz wants moviegoers to come away with the idea that changing your life is "as simple as making a decision".