问题 选择题

某同学在实验室中进行如下实验:

编号IIIIII
实验
现象没有明显变化,溶液仍为无色有白色沉淀生成,溶液为蓝色有无色气体放出
以下结论正确的是

A.I中混合前后溶液中各离子种类、个数均不变

B.II中反应前后溶液中Cu2+、Cl浓度均未变

C.II中BaCl2替换为Ba(NO3)2溶液,发生的离子反应相同

D.III中发生的反应属于置换反应,不属于离子反应

答案

答案:C

题目分析:消耗2个数虽然不变但种类有氢离子变成了钠离子A错。加氯化钡溶液,体积增大浓度应减小 B错。都是钡离子与硫酸根离子反应生成硫酸钡沉淀 C正确。在溶液中有离子参加的化学反应称为离子反应,应属于离子反应 D错。

单项选择题

I was a single parent of four small children, working at a low paid job. Money was always tight, but we had a (1) over our heads, food on the table, clothes on our backs, and if not a lot, always (2) . Not knowing we were poor, my kids just thought I was (3) . I’ve always been glad about that.

It was Christmas time, and although there wasn’t (4) for a lot of gifts, we planned to celebrate with a family party. But the big (5) for the kids was the fun of Christmas (6) .

They planned weeks ahead of time, asking (7) what they wanted for Christmas. Fortunately, I had saved MYM120 for (8) to share by all five of us.

The big (9) arrived. I gave each kid a twenty-dollar bill and (10) them to look for gifts of about four dollars each. Then everyone scattered. We had two hours to shop; then we would (11) back at the "Santa’s Workshop"

Driving home, everyone was in high Christmas spirits, (12) my younger daughter, Ginger, who was unusually (13) She had only one small, flat bag with a few candies—fiftycent candies I was so angry, but I didn’t say anything (14) we got home. I called her into my bedroom and closed the door, (15) to be angry again. This is what she told me.

"I was looking (16) thinking of what to buy, and I (17) to read the little cards on the ’Giving Trees’. One was for a little girl, four years old, and all she (18) for Christmas was a doll. So I took the card off the tree and (19) the doll for her. We have so much and she doesn’t have anything. "

I never felt so (20) as I did that day.

10().

A.shopping 

B.travelling 

C.parties 

D.greetings

单项选择题