题干

A、B、C、D是初中化学常见的物质,这四种物质中均含有同一种元素.其中A为无色气体单质,B、C为氧化物,且B为有毒气体,D是大理石的主要成分.它们之间的部分转化关系如图所示(图中反应条件及部分反应物、生成物已省略).

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同类题1

对下表中所列待测物质的检测,所选用的试剂及预期结果都正确的是
 
待测物质
检测试剂
预期显色结果
①
DNA
甲基绿
红色
②
脂肪
苏丹Ⅲ
橘黄色
③
淀粉
斐林试剂
蓝色
④
蛋白质
双缩脲试剂
紫色

同类题2

根据短文理解,选择正确答案。

    Andy never wanted to go to bed on time. His parents had explained to him how important it was to go to bed early and get a good rest. But Andy paid no attention to them, and they didn't know what to do until one weekend when they were visiting Andy's grandparents.

    Grandpa Peter heard all about it and said, "This sounds like a job for Tubby." So Andy's parents loaded the cat onto the car and returned home.

That night, at bedtime, the same problem happened. Andy didn't want to go to bed, and even though his parents waited a while to see if Tubby would solve the problem, nothing happened.

    Hours later, Andy finally decided to go to bed. But what a surprise when he entered his bedroom! Tubby was in his bed, totally sprawling out, pot-belly in the air, and snoring like an express train.

    Andy tried to move the cat, but there was no way of moving him an inch. That night he hardly slept, lying on one tiny corner of his bed.

    The next day the same thing happened, even though Andy was much more tired from not having slept well. When the third day arrived, he had understood that if he wanted to sleep in his bed, he would have to get into it before Tubby did. That night, when his parents only started to mention the topic of bedtime, Andy rushed upstairs and dived into bed. His parents could not believe it. They knew nothing about Tubby in the bed, nor did they understand why Andy went to bed on time without complaint. They were so happy about this that they stayed up quite late, celebrating.