题干

下列实验操作正确且能达到预期目的的是
 
实验目的
操   作
① 
比较水和乙醇中羟基氢的活泼性强弱
用金属钠分别与水和乙醇反应
② 
欲证明CH2=CHCHO中含有碳碳双键
滴入KMnO4酸性溶液,看紫红色是否褪去
③ 
欲除去苯中混有的苯酚
向混合液中加入浓溴水,充分反应后,过滤
④ 
证明SO2具有漂白性
将SO2通入酸性KMnO4溶液中
⑤ 
比较确定铜和镁的金属活动性强弱
用石墨作电极电解Mg(NO3)2、Cu( NO3)2的混合液
⑥ 
确定碳和硅两元素非金属性强弱
测同温同浓度Na2CO3和Na2SiO3水溶液的PH

A:①⑤⑥

B:①②⑥

C:①③④

D:②④⑥

上一题 下一题 0.0难度 选择题 更新时间:2017-11-03 06:02:23

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A

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    The Crowne Plaza Hotel in Copenhagen is offering a free meal to any guest who is able to produce electricity for the hotel on an exercise bike linked to a generator (发电机). The idea is to get people fit and reduce their carbon footprint. Guests will have to produce at least 10 watt hours of electricity — roughly 15 minutes of cycling for someone of average fitness. Guests staying at Plaza Hotel will be given meal tickets worth $ 36 once they have produced 10 watt hours of electricity. The bicycles will have smart phones attached to the handlebars measuring how much power is being generated for the hotel.

    The plan, a world-first, will start on 19 April and run for a year. Only guests staying at the hotel will be able to take part. Frederikke Toemmergaard,hotel spokeswoman, said, “Many of our visitors are business people who enjoy going to the gym. There might be people who will cycle just to get a free meal, but generally I don't think people will take advantage of our programme.”

    Copenhagen has a long-standing cycling tradition and 36 % of locals cycle to work each day, one of the highest percentages in the world, according to the website visitcopenhagen. dk. US environmental website treehugger. com recently voted Copenhagen the world's best city for cyclists. “Because Copenhagen is strongly connected with cycling, we felt the bicycle would work well as a symbol of the hotel's green profile (形象).”

    If successful,the electric bicycle meal programme will be spread to all Crowne Plaza hotels in the UK, the hotel said in a statement.