题目

使用红磷燃烧的方法测定空气中氧气的含量。  (1)写出红磷在空气中燃烧的化学方程式：____________________。 (2)在集气瓶中加入少量水，并将水面上方空间分成5等份，如图装置所示。待红磷熄灭并冷却后，打开弹簧夹，观察到烧杯中的水进入集气瓶，瓶内水面最终上升约至1刻度处。由此可知氧气约占空气总体积的________。 (3)实验后发现测定空气中氧气的含量偏低，造成这种结果的可能原因是________________________________(填一种即可)。 (4)已知五氧化二磷能A: Hello! This is Kanghui traveling information center of Harbin. What can I do for you? B: Hello! I'd like to have a trip next week.A: 【1】B: I've no idea yet. Could you give me some good suggestions? A: Sure. 【2】 It's so beautiful at the moment.B: That sounds good. But I am afraid of climbing mountains. A: I'm sorry. 【3】 There's a two-day trip.B: Good idea! I enjoy water.A: Okay. Would you like to go by train or by bus? B: 【4】 It won't take much time.A: How many people will go there together? B: Three. My husband, my son and I.A: Three people, by train. And you need to stay one night in Mudanjiang City. 【5】B: Thanks.A.What about going to Jingpo Lake?B.Which place do you want to go to?C.Mount Songfeng may be a good choice.D.By bus.E.I will book a family room for you.F.I'd like to take the train.G.You need to book a single room (单人间).