Answer:
1. 2h(2) + 1O(2) -> H(2)O
2 1CH(4) + 2O(2) -> 1CO(2) + 2H(2)O
3. 1N(2) + 3H(2) -> 2NH(3)
4. 2P + 5O(2) -> 2P(2)O(5)
