题干

下列实验操作及现象能够达到对应实验目的是(   )

选项

实验操作及现象

实验目的

A

将SO2通入品红溶液中,品红溶液褪色;加热褪色后的品红溶液,溶液恢复红色

验证亚硫酸的不稳定性

B

常温下,向饱和Na2CO3溶液中加少量BaSO4粉末,过滤,向洗净的沉淀中加稀盐酸,有少量气泡产生

证明常温下

Ksp(BaCO3)>Ksp(BaSO4

C

常温下,测定物质的量浓度相同的盐酸和醋酸溶液的pH:盐酸pH小于醋酸pH

证明相同条件下,在水溶液中HCl电离程度大于CH3COOH

D

将浓硫酸与碳混合加热,直接将生成的气体通入足量的石灰水,石灰水变浑浊

检验气体产物种CO2的存在

A:A  

B:B  

C:C  

D:D

上一题 下一题 0.0难度 选择题 更新时间:2012-05-30 07:46:26

答案(点此获取答案解析)

C

同类题1

请阅读下面短文,并按照要求用英语写一篇150词左右的文章。

     In recent years, internet voting has become increasingly popular in China. People not only cast on-line votes themselves, but also urge others to vote for competitions like the “Most Beautiful Teacher” and the “Cutest Baby”.

      Li Jiang, a high school student, is invitedto vote in the “ Best Police Officer " competition,organized by the local government to let the public have a better understanding of police officers’ daily work. Li Jiang visits the website and reads all the stories. He is deeply moved by their glorious deeds. He is already thinking of becoming a policeman himself in the future.

        Su Hua is invited by his uncle to vote for his cousin in the “ Future Singer" competition. He has already received three similar invitations this week. His uncle tells him that if his cousin wins the competition, the family will win an overseas tour for free. Su Hua likes his cousin very much, but he finds other singers perform even better. To vote, or not to vote? This is a question that troubles him very much.

【写作内容】

①用约30个单词写出上文概要;

②用约120个单词阐述你对网络投票的看法,并用2 ~3个理由或论据支撑你的看法。

【写作要求】

①写作过程中不能直接引用原文语句;

②作文中不能出现真实姓名和学校名称;

③不必写标题。

【评分标准】

内容完整,语言规范,语篇连贯,词数适当。