关于胶体和溶液的区别，下列叙述中正确的是（） A．溶液中_爱下问搜题

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问题选择题

关于胶体和溶液的区别，下列叙述中正确的是（　　）

A．溶液中溶质粒子有规律运动，而胶体粒子无规律运动

B．将1L2mol•L^-1的FeCl₃溶液加到沸水中，加热使之反应完全，得Fe（OH）₃的胶粒数为2N_A

C．一束光通过胶体时有光亮的“通路”，通过溶液时无此现象

D．溶液中溶质微粒一定带电，且通电后，溶质粒子向两极移动

答案

A．溶液中的离子呈现自由态，其运动无规律可言，胶体的分散质粒子在显微镜观察下呈现也是无规则运动，故A错误；

B．将1L2mol•L^-1的FeCl₃溶液加到沸水中，加热使之反应完全，得Fe（OH）₃的胶体，该反应为可逆反应且氢氧化铁胶体的胶粒是氢氧化铁的集合体，胶粒数小于2N_A，故B错误；

C．丁达尔效应是胶体的独有性质，胶体分散质粒子直径在1nm～100nm之间，一束光通过胶体时，胶粒对光产生散射，有光亮的“通路”，溶液分散质粒子直径小于1nm，通过溶液时无此现象，故C正确；

D．通电时，溶液中的溶质粒子是电解质，电离出的阴阳离子分别向两极移动，如氯化钠溶液，通电时，氯离子移向阳极，钠离子移向阴极，若溶质是非电解质不移向电极，如蔗糖溶液，故D错误；

故选C．

完形填空

My friends and I had just finished lunch at a hotel when it started to pour 1 . When it became lighter, I decided to get my car, which was 2 at my office three streets away.
My friends argued that I shouldn’t go, mainly because I was seven months pregnant then. I assured them that I’d be very 3 .
I walked out of the 4 and started making my way to the car. At the traffic junction, a van stopped and the passenger got off with an umbrella. Before I knew what was happening, he walked right beside me and told me he’d escort(护送) me to my 5 . I was very embarrassed and declined(辞谢), but he was very 6 .
During our 7 , he kept telling me to walk slower, as the ground was 8 . When we got to the car park, I 9 him and we parted ways. I did not get his 10 and may not even recognise him now. Did he 11 stop for me? I’ll never know.
So how did I pay it forward? I was at home when I 12 two Indian construction workers walking in the heavy rain. They were probably on their way to the construction 13 near my estate, which was a long walk in. I went out and passed them an umbrella. I told them they should take the umbrella and 14 it. They were very grateful and like me, probably wondered why a 15 was offering such kindness.

A．destination

单项选择题

根据《国务院办公厅关于进一步加强乳品质量安全工作的通知》的要求，各地工商部门要加大对婴幼儿配方乳粉经营单位的监督检查力度，以婴幼儿配方乳粉批发企业、大中型超市为重点对象，明确监管责任人，实行每（）抽检。

A、日

B、周

C、月

D、年