In many parts of the world, there are four seasons: spring, summer, fall and winter. In the U.S., there are only three: football, basketball and baseball. If you want to know what season it is, just have a look at what people are playing.

    For many people in the U.S., sports are not just for fun. They're almost a religion. Thousands of sports fans buy expensive tickets to watch their favourite teams and athletes play in person. Other fans watch the games at home. The most devoted sports buffs never miss a game. Many a wife becomes a “sports widow (寡妇)” during her husband's favorite season.

    America's devotion to athletics has created a new class of wealthy people: professional athletes. Sports stars often receive million -dollar salaries. Some even make big money appearing in advertisements for soft drinks, shoes and even toiletries (化妆品).

    Sports are an important part of Americans' culture. Throughout their school life, Americans learn to play many sports. All students take physical education classes in school. Some try out for the school teams, while others join school sports leagues. Athletic events at universities attract scores of fans and benefit the whole community.

某同学模仿物理课上学到的“串联电路”，设计了如下气体制取与性质验证的组合实验．打开分液漏斗活塞后，A中出现大量气泡，B中白磷燃烧，C中液面下降．请看图回答问题：

（1）B中白磷能够燃烧的原因是____ ．

（2）D中反应的化学方程式为____ ．

（3）E中的实验现象是____．

（4）用F装置收集气体的依据是____ ．

（5）人教版高中教材《化学1》显示，过氧化钠（Na₂O₂）和二氧化碳反应生成碳酸钠和氧气，化学方程式为2Na₂O₂+2CO₂═2Na₂CO₃+O₂．小翔同学和小何同学分别设计了图甲和图乙的实验装置，检查气密性良好后进行实验验证．预热后对试管进行加热（2NaHCO₃$\stackrel{△}{=}$Na₂CO₃+CO₂↑+H₂O）．观察到图甲浓硫酸中有气泡产生，蚊香熄灭．浓硫酸的作用____ ．观察图乙中的蚊香燃烧更剧烈，说明有氧气产生．由资料和实验可得出的结论是____ ．

下列物质溶于水时，溶液温度明显降低的是（　　）