人造地球卫星用到的一种高能电池——银锌蓄电池，其电极分别是Ag2O和Zn，电解液是KOH溶液。该电池的电极反应式为Zn+2OH--2e-=Zn(OH)2，Ag2O+H2O+2e-=2Ag+2OH-。下列说法中正确的是（ ）
①锌为负极，Ag2O为正极；②放电时，正极附近溶液OH-浓度增大；③工作时电流由Ag2O极经外电路流向Zn极；④溶液中阴离子向正极方向移动，阳离子向负极方向移动
A．①
B．①②④
C．①②③
D．①②③④
答案：C
题目分析：根据电池反应式Ag2O+Zn=2Ag+ZnO知，失电子的物质作负极，得电子的物质作正极，原电池放电时，电子从负极沿导线流向正极；根据电池电极附近氢离子或氢氧根离子浓度的变化判断溶液PH值的变化。
④溶液中阴离子向负极方向移动，阳离子向正极方向移动，故错。故选C。
故选C。
点评：本题考查了原电池原理，难度不大，明确原电池正负极的判断方法、外电路中电子的流向、电极附近离子浓度的变化导致溶液PH值的变化即可解答本题。
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| I think we should try to find a happy memory, something to lift us up on those unpleasant days. I`m saying this because I think I just found mine! I had some work in Glasgow then. I was on a really 1 schedule, which meant I would have no time for myself all day. I was having one of those days, when the train was completely 2 and the conversation going on around me seemed to be particularly 3 . Besides, I had a bit of a headache. 4 quickly across the station hall, I fished some 5 from my pocket. There was usually someone at the exit 6 the Big Issue (a magazine that helps homeless folk earn a living). 7 the crowd parted ways at the bottom of the hall, I saw someone selling the Big Issue. She really looked like she`d been sleeping 8 . Her clothes were 9 and she obviously hadn`t had a scrub up (擦洗) for quite a while. As I 10 the exit, I saw that she was 11 from side to side. At first I thought she was trying to keep 12 against the biting wind. But she wasn`t. She was moving in time to a 13 . I couldn't hear her, but I could see her lips moving. When I got closer, I saw a white 14 hanging from her elbow and noticed that she had sunken eyes. She was 15 , dirty and living on streets. I came closer and through the 16 of the traffic I could hear her 17 the immortal (不朽的) line,"…And I think to myself, what a wonderful world!". I bought her last magazine for twice what I'd originally 18 . She thanked me, and 19 her belongings and went tapping off along the pavement -still singing! So, I have my happy 20 for the day, and I think it will stay with me a long,long time. | ||||
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