水电解制氢过程中“氢中氧”表计指示应小于()才合格。
A.0.2%;
B.0.3%;
C.0.4%;
D.0.5%。
参考答案:A
同义句
1. There are five bananas in his box.
_______ ________ five bananas in the box.
2. We have a good time in school.
We ________ ________ in school.
3. I get to the library at six.
I _________ ________ the library at six.
4. There is a pay phone in the neighborhood.
There's a pay phone ________ _________.
5. My aunt buys hamburgers for five dollars.
My aunt ________ five dollars ________ hamburgers.
下图是常见物质之间的相互反应关系,其中甲、乙、丙、丁都是固体,且甲、乙、丙呈黑色,丁呈红色;A 和B含有相同的元素组成。请你推断:
(1)写出下列物质的名称:
甲: ,
乙: ,
丙: ;
(2)写出图中③反应的化学方程式
(3)写出G的一种用途_______ _________。
(4)写出一个符合反应①的化学方程式 。
(5)将E通入滴有紫色石蕊试液的水中,现象是 ,产生这种现象的原因是 。