题目内容：

简单英文化学问题!
writing chemical equations!
1.copy the following equation into your book and balance them:
(1)H2+O2-H2O (2)N2+H2-NH3 (3)P+O2-P2O5
希望高手 讲解下 ,还有讲解下balancing the equation!谢啦!
我初学者