If a sample of pure hydrogen gas is ignited very carefully, the hydrogen burns gently, combining with the oxygen gas of the air to form water vapor. Write the unbalanced chemical equation for this reaction.

Answer 1

H2(g) + O2(g) --> H2O(l) unbalanced.
2H2(g) + O2(g) ==> 2H2O(l) balanced.

Answer 2

H2(g)+O2(g)-->H2O(g)

Answer 3

2h+o2=h2o2