已知W、X、Y、Z四种短周期主族元素在周期表中的相对位置右图所示，下列有关说
法正确的是
| W | X |
| Y | Z |
B．Y元素的原子半径可能比X元素的小
C．Z的气态氢化物的稳定性一定比X的强
D．Z的原子序数可能是X的原子序数的2倍
答案：D
题目分析：根据元素周期律，Y和W同主族，Y的还原性比W强，但氧化性比W弱，故A选项错误；同周期主族元素半径从左往右依次减小，同主族从上到下依次增大，故Y元素半径一定比X元素的大，B选项错误；同主族元素从上到下气态氢化物的稳定性依次减弱，故Z的比X的弱，C选项错误；根据四种短周期元素的相对位置可知，W、X是第二周期因素，Y、Z是第三周期因素，若X、Z分别为氧元素和硫元素时，Z的原子序数是X的原子序数的2倍，故D选项正确。
点评：本题考查学生对元素周期律的掌握，分析此题时，应对元素周期表的“位构性”三者有较好的把握和理解。难度较小。
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