题目

下列有关实验的操作正确的是( ) 实验 操作 A． 配制稀硫酸 先将浓硫酸加入烧杯中，后倒入蒸馏水 B． 排水法收集KMnO4分解产生的O2 先熄灭酒精灯，后移出导管 C． 浓盐酸与MnO2反应制备纯净Cl2 气体产物先通过浓硫酸，后通过饱和食盐水 D． CCl4萃取碘水中的I2 先从分液漏斗下口放出有机层，后从上口倒出水层A. A B. B C. C D. D8、A: Excuse me, do you know where the chemistry lab is? B: Yes. It’s just on the fifth floor of this b____76____. A: How often do you do c___77____ experiments there? B: Twice a week. A: Can you go there without a t___78___? B: No. That’s not allowed. A: What does the teacher often tell you to do when you are doing an e____79___? B: He often tells us to look c____80____ and follow the i____81____. A: What will you do when you finish the experiment? B: We must put e___82_____ back in the cupboards and wash our hands. A: Right. It is very i___83____ to keep the lab clean. B: Yes, safe as well. We must turn off the e____84____ before l___85___ the lab. 评卷人 得分 三、选择题 （每空？ 分，共？ 分）