下列各组离子在指定溶液中能大量共存的是①无色溶液中:K+、Cu2+、Na+、、②使pH=11的溶液中:、Na+、、③加入Al能放出H2的溶液中:Cl-、、、④能使pH试纸变为蓝色的溶液:Na+、Cl-、S2-、⑤酸性溶液:Fe2+、Al3+、、I-、Cl-A.①⑤ B.①③ C.②④ D.①② 答案:C 由于Cu2+和都有颜色,故①不合题意;无论是强酸性或强碱性溶液中,加入Al都能放出H2,但无论在强酸性或强碱性溶液中,都不能大量共存,故③不合题意;酸性溶液中,与Fe2+、I-因发生氧化还原反应不能共存,故⑤不合题意。答案选C。
听句子,选择恰当的答语。每个句子读两遍。
( )1. A. That's OK. ( )2. A. I'm thirsty. ( )3. A. Just a little , please.( )4. A. Very well. ( )5. A. No, I didn’t.
B. The same to you. B. Some orange juice.B. That's nice. B. Very good. B. Not yet.
C. I'm glad you like it. C. Yes, a cake please. C. You'd better have a good rest.C. Very hard. C. No, I don’t.