问题 选择题

所含溶质质量、溶液体积都相等的稀硫酸分别与足量的颗粒大小和形状几乎相同的镁、铁、锌三种金属反应,下列图象能正确表示生成氢气质量与反应时之间关系的是(  )

A.

B.

C.

D.

答案

A、根据题意完全反应后放出氢气质量相等;而由关系图,三个反应最终放出氢气质量不相等,与反应事实不符;故A不正确;

B、根据题意完全反应后放出氢气质量相等并且镁反应速率大最先完全反应,其次为锌,铁最后完成反应;关系图所表示与反应事实相符;故B正确;

C、根据题意镁反应速率大最先完全反应,其次为锌,铁最后完成反应;而由关系图,铁先于锌完成反应,与反应事实不符;故C不正确;

D、根据题意完全反应后放出氢气质量相等;而由关系图,三个反应最终放出氢气质量不相等,与反应事实不符;故D不正确;

故选B.

单项选择题
单项选择题

All her life, my mother wanted busy children. It was very important that her house should remain at all times clean and tidy.
You could turn your back for a moment in my mother’s house, leave a half written letter on the dining table, a magazine open on the chair, and turn around to find that my mother had "put it back where it belonged," as she explained. My wife, on one of her first visits to my mother’s house, placed a packet of biscuits on an end table and went to the kitchen to fetch a drink. When she returned, she found the packet had been removed. Confused, she set down her drink and went back to the kitchen for more biscuits, only to return to find that her drink had disappeared. Up to then she had guessed that everyone in my family held onto their drinks so as not to make water rings on the end tables. Now she knows better.
These disappearances had a confusing effect on our family. We were all inclined to forgetfulness, and it was common for one of us, upon returning from the bathroom, to find the every sign of his work in progress had disappeared suddenly. "Do you remember what I was doing" was a question frequently asked, but rarely answered.
Now my sister has developed a secondhand love of clean windows, and my brother does the cleaning in his house, perhaps to avoid having to be the one to lift his feet. I try not to think about it too much, but I have at this later time started to dust the furniture once a week.

This passage mainly tells us that

A.my mother often made us confused
B.my family members had a poor memory
C.my mother helped us to form a good habit
D.my wife was surprised when she visited my mother