题干

逻辑推理时化学学习常用的思维方法,某校研究性学习小组在做“寻找新的催化剂”课题时,发现将生锈的铁钉放到过氧化氢溶液中,也可以加快过氧化氢的分解速率.于是,他们对此展开探究.

【提出问题】:什么物质是该反应催化剂?

【查阅资料】铁与氧气、水反应生成铁锈,铁锈的主要成分为氧化铁.

上一题 下一题 0.0难度 选择题 更新时间:2018-02-24 07:48:43

答案(点此获取答案解析)

同类题1

阅读理解

    In America there are many more cars than in China. Maybe the number of cars in California is the same as the number in China. But there are fewer traffic jams and accidents in America than in China. We hardly see traffic police in the street, but all drivers obey strictly traffic rules, and people hardly find that someone does not obey traffic rules in the street.

    About American traffic rules, there are many better terms, such as:

    Stop line:There are stop lines in all crossing without traffic light(some have two stop lines and others have four stop lines);all cars must stop while meeting the stop line.

Traffic lights:There are traffic lights in the crossing of the road. Cars may almost turn every direction;the traffic lights can give signals step by step including U—rum. There is a kind of middle lane of turning left. When a driver wants to turn left in the road. he may enter into the middle lane (车道)of turning left and give a signal of turning left. when he thinks it's safe, he may turn left.

Specific item:Such as parking, there are three kinds of lines(its colors are white, blue or red)in the roadside. Every line may park different kinds of cars. There are many streets in some residential areas(住宅区), and no car can park at any time or any period of time.

  About the priority(优先权)of passengers and cars:At any case, passengers have the

priority to cars. But only after passengers have passed the road and gotten the top of sidestep, cars may go ahead. In general, traffic rules of America are very specific, convenient and safe.