题干

醋是家庭中不可缺少的调味品之一,同时,醋还具有较强的杀灭细菌、抑制病毒的作用.另外,醋可使胃中酸性增强,促进食欲,帮助消化,对于胃酸较少的人更是一剂良药.醋中的主要成分是醋酸,其化学式为CH3COOH.下列有关叙述中错误的是(   )

A:醋酸的水溶液呈酸性,其pH大于7,滴入紫色石蕊试液显蓝色

B:醋酸能与氢氧化钠溶液反应生成醋酸钠和水,该反应为中和反应

C:用醋可以洗净铝制品的污垢,还可除去暖壶、水壶中的水垢

D:醋酸是由三种元素组成的化合物,一个醋酸分子由8个原子构成

上一题 下一题 0.0难度 选择题 更新时间:2019-03-13 06:44:41

答案(点此获取答案解析)

A

同类题4

    The mystery stories of Sir Arthur Conan Doyle are famous all over the world.
    The detective in his stories is called Sherlock Holmes. He solves mysteries in a most surprising way. His assistant, Dr Watson, watches with admiration and then writes up the story of the mystery afterwards.
    This is a useful story writing skill. Because Watson is not very clever, the story remains a mystery until the end. The readers can sometimes pick up some clues before he does! Then, to make Watson understand the mystery, Holmes has to explain it all, step by step. So we, the readers, get to see it step by step too. Watson is almost as good a character in the story as Sherlock Holmes!
    The very first time they meet, Holmes greatly surprises Watson. When they are first introduced, Holmes says to Watson, ‘How do you do? I see you have been to Afghanistan(阿富汗).’
    Watson is too amazed by this to ask Holmes how he knows this. Watson has, indeed, been to Afghanistan. Later, he asks Holmes about it. Holmes explains that there is nothing magical about what he does. He gets to know it all by very, very careful observation(观察).
Observation One
    Watson was introduced to Holmes as a doctor. Yet Holmes thought that the way he stood and walked made him seem like a soldier. So, this meant he was probably an army doctor.
Observation Two
    Watson's face was quite dark skinned. But his wrists were pale. So his dark face was probably sun burnt. This meant that he had been to a hot, sunny country.
Observation Three
    At the time, the British army had soldiers at bases in many parts of the world. So there were still a lot of places to choose from. However, Holmes saw that Watson looked very tired and he was always holding his left arm, as if it was painful. So, he had probably been with the army to a place where they were fighting. There was only one place where the British army was fighting at that time: Afghanistan.