问题 选择题

实验室利用过氧化氢、氯酸钾、高锰酸钾都可以制取氧气,其原因是(  )

A.都属于氧化物

B.都含有氧气

C.都含有氧分子

D.都含有氧元素

答案

答案:D

题目分析:根据物质的组成分析。

A、氧化物是由两种元素组成,并且其中一种元素为氧元素的化合物,而氯酸钾和高锰酸钾中虽都有氧元素,但它们都由三种元素组成,错误;

B、过氧化氢、氯酸钾、高锰酸钾三种物质都是纯净物,即由一种物质组成,故都不含氧气,错误;

C、氧气是由氧分子构成的,由于三种物质中都不含氧气,故也就不含氧分子,错误;

D、由于在化学变化中元素的种类不变,氧气是由氧元素组成的,因此制取氧气的物质中必须含有氧元素,根据三物质的组成可知,它们都含氧元素,正确。故选D

点评:熟练掌握常见物质的组成,以及物质的分类方法等知识,是解答本题的关键。

完形填空

Long long ago, there was a man whose name was Frank. He loved his  46  very much. A special day was coming. It was his wife’s birthday. Frank decided  47  something for her.

The next day he  48  home and said to his wife, “I bought something  49  you.” “Thank you!” said his wife  50 . “What have you bought for me?” “I’ve bought a gold ring. Here it is.” He took it out for his wife to see. Carelessly, he dropped it onto the ground. He began to look for it on the ground, 51  it was dark in the house and he could not see  52 . Then he went out and began to look for it in the street.

He looked and looked. After a while, a friend came along. “What’s the matter with you?” asked his friend. “I am  53  for my ring. It was for my wife. But I lost it just now.” said the poor man. “  54  did you lose it?” “I lost it in my house.” “You lost your ring in your house, but you are looking for it in the street. How foolish you are!” “Ah,” said the man, “but it is dark in my house. I will never find it there. Anyhow, here in the street, it is much  55 . I can see everything more clearly.” My dear friend, do you think Frank could find his gold ring in the street?

小题1: A. wife         B. daughter      C. son

小题2: A. to show  B. to buy  C. to cook

小题3:  A. go B. goes     C. went

小题4: A. for   B. with     C. to

小题5: A. angrily     B. sadly    C. happily

小题6: A. but  B. so         C. because

小题7:  A. something    B. anything       C. nothing

小题8:  A. asking   B. calling  C. looking

小题9:A. Where       B. When   C. Why

小题10: A. darker     B. brighter        C. harder

单项选择题