【单选题】下列实验操作与预期目的或所得结论一致的是
A.
用铂丝蘸取某溶液进行焰色反应,火焰呈黄色,证明该溶液中一定不含有K +
B.
向浓度均为0.1 mol·L - 1 NaCl和NaI混合溶液中滴加少量AgNO 3 溶液,产生黄色沉淀,说明K sp (AgCl)>K sp (AgI)
C.
向某溶液中加入硝酸酸化的Ba(NO 3 ) 2 溶液,出现白色沉淀,说明该溶液一定含有SO 4 2 -
D.
在乙酸、乙醇与乙酸乙酯的混合物中加入适量饱和烧碱溶液充分混合后分液,可得到较纯净的乙酸乙酯
【单选题】E是下列物质中的一种,E的焰色反应为黄色,E加AgNO 3 和稀HNO 3 溶液有白色沉淀,E是
【单选题】下列说法正确的是 选项 实验 解释或结论
A.
用洁净的Pt丝蘸取某溶液进行焰色反应,火焰呈黄色 该溶液中一定含有Na + , 无K +
B.
用洁净的玻璃管向包有Na 2 O 2 的脱脂棉吹气,脱脂棉燃烧 CO 2 、H 2 O与Na 2 O 2 反应是放热反应
C.
向溴水中滴入植物油,振荡后,油层显无色 溴不溶于油脂
D.
将硫酸酸化的H 2 O 2 滴入Fe(NO 3 ) 2 溶液,溶液变黄色 H 2 O 2 的氧化性比Fe 3+ 强
【单选题】听力原文:M Tell me about your work experience, Susan. F Well, I've been working as a bank cashier for six years. M And what else have you done? F I trained as a secretary and later went to work for Morley...
C.
She worked in an office.
【简答题】Work in moderation is agreeable as well as ______ (health)to human beings.
【单选题】-Does the new programme work well on tourism. -Yes. It ____ more tourists. [ ]