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问题 选择题

下列电子排布式对应的元素原子，半径最大的是 （   ）。

A．1s22s22p63s23p64s1

B．1s22s22p63s23p63d104s1

C．1s22s22p63s23p63d104s24p5

D．1s22s22p63s23p 63d54s2

答案

答案：A

题目分析：1s22s22p63s23p64s1 为K原子的核外电子排布式；1s22s22p63s23p63d104s1为Cu原子的核外电子排布式；1s22s22p63s23p63d104s24p5  为Br原子的核外电子排布式；

1s22s22p63s23p 63d54s2为Mn原子的核外电子排布式，四种元素都是第四周期的元素，根据用一个周期的原子半径从左往右减少可以知道K的原子半径最大，故本题的答案选择A。

点评：本题考查了核外电子排布式，原子半径，属于对基础知识的考查，本题难度不大。

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比较文学诞生的标志是比较文学杂志的出现、（）、比较文学作为一门正式的课程进入高等学校的课堂和比较文学学位论文与工具书的出现。
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It is difficult to imagine what life would be like without memory. The meanings of thousands of everyday perceptions, the bases (51) the decisions we make, an d the roots of our habits and skills are to be (52) in our past experiences, which are brought into the present (53) memory.

Memory can be defined as the capacity to keep (54) available for later use. It includes not only "remembering" things like arithmetic or historical facts, but also any change in the way an animal typically behaves. Memory is (55) when a rat gives up eating grain because he has sniffed something suspicious in the grain pile. Memory is also involved when a six-year-old child learns to swing a baseball bat.

Memory (56) not only in humans and animals but also in some physical objects and machines. Computers, for example, contain devices for storing data for later use. It is interesting to compare the memory-storage capacity of a computer (57) that of a human being. The instant-access memory of a large computer may hold up to 100000 "words" —ready for (58) use. An average American teenager probably recognizes the meanings of about 100000 words of English. However, this is but a fraction of the total (59) of information which the teenager has stored. Consider, for example, the number of facts and places that the teenager can recognize on sight. The use of words is the basis of the advanced problem-solving intelligence of human beings. A large part of a person’s memory is in terms of words and (60) of words.

51（）。

A. of

B. to

C. for

D. on
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