2008年北京奥运会主体育场因外形像“鸟巢 (The Bird Nest)而得名.有一种叫五硼烷的物质结构也好似鸟巢.其化学式为B5H9．下列有关五硼烷的说法错误的是( )A.五硼烷属于化合物B.五硼烷的相对分子质量为64gC.五硼烷中硼元素和氢元素的质量比为55:9D.1个五硼烷分子由5个硼原子和9个氢原子构成题目和参考答案——青夏教育精英家教网—

题目内容

2008年北京奥运会主体育场因外形像“鸟巢”（The Bird Nest）而得名，有一种叫五硼烷的物质结构也好似鸟巢，其化学式为B₅H₉．下列有关五硼烷的说法错误的是（　　）

A、五硼烷属于化合物

B、五硼烷的相对分子质量为64g

C、五硼烷中硼元素和氢元素的质量比为55：9

D、1个五硼烷分子由5个硼原子和9个氢原子构成

分析：A、由不同种元素组成的纯净物是化合物．
B、根据相对分子质量为构成分子的各原子的相对原子质量之和，进行分析判断．
C、根据化合物中各元素质量比=各原子的相对原子质量×原子个数之比，进行分析判断．
D、根据五硼烷分子的构成进行分析判断．

解答：解：A、五硼烷是由硼元素、氢元素两种元素组成的纯净物，属于化合物，故选项说法正确．
B、五硼烷的相对分子质量是11×5+1×9=64，不是64g，故选项说法错误．
C、五硼烷中硼元素和氢元素的质量比为（11×5）：（1×9）=55：9，故选项说法正确．
D、由五硼烷的化学式可知，一个五硼烷分子是由5个硼原子和9个氢原子构成的，故选项说法正确．
故选：B．

点评：本题难度不大，考查同学们结合新信息、灵活运用化学式的含义与有关计算进行分析问题、解决问题的能力．

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