* Which equation is NOT balanced?
O 2 Hz + 02 > 2 H20
4 H2 + 2 02 ---> 4H20
H2 + H2 + O2 > H2O + H20
2 H2 + 02 > H20
None of the above

2H₂ + O₂ → H₂O

Explanation:

The unbalanced equation is

          2H₂ + O₂ → H₂O

In a balanced chemical equation, the number of moles of species on both sides of the expression must be the same.

                2H₂ + O₂ → H₂O

                                       Reactant                                 Product

                                      H          O                                   H         O

Number of moles          4           2                                   2           1

We see that the number of hydrogen and oxygen on both sides of the expression differs significantly.