题目

Bank holidays! We all love them!A bank holiday is an English term for a public holiday. During the day banks and offices are closed and a lot of people have a day off work. In the UK, people only get eight bank holidays in one year. 【1】People in Colombia are much luckier. There are twenty bank holidays for the whole country in one year! And there can be even more, depending on which region(地区) you live in. 【2】 As in the UK, most of the bank holidays in Colombia exist for religious reasons.【3】 One such example is Independence Day on 20 July every year. This is just like Bastille氧化铝有二种变体，一种是a-Al2O3，另一种是g-Al2O3，g-Al2O3可用Al(OH)3在723K时加热制得，它不耐酸；a-Al2O3是天然刚玉的主要成分，硬度很高，且对酸有极强稳定性。a-Al2O3，可以用g-Al2O3于高温煅烧制得，已知氧化铝可由铝铵明矾加热制得，铝铵明矾[NH4Al(SO4)2×12H2O]受强热分解的产物为Al2O3、NH3、N2、SO3、SO2和H2O。 （1）写出铝铵明矾强热分解反应的化学方程式____________，在此反应中氧化产物与还原产物的物质的量之比为_________。 （2）把上述反应中的Al2O3加入适量氧化铬在氢氧焰上强热熔融后，使其结晶可以制成人造红宝石，可用于作激光器材和装饰品。所得人造红宝石是哪种Al2O3的变体？_____________，怎样用简便方法说明它确实是该种Al2O3的变体？________________。 （3）氧化铝陶瓷是一种重要的结构材料，工业上用它来制造坩埚、高温炉管，是利用它的__________特性；用它制造刚玉球磨机，是利用它的________特性。