1) Chemical equation (unbalanced).
[tex]N_2H_{4\text{ }(g)}+H_2O_{2\text{ }(g)}\rightarrow N_{2\text{ }(g)}+H_2O_{(g)}[/tex]List the elements in the reactants and in the products.
Reactants
N: 2
H: 6
O: 2
Products
N: 2
H: 2
O: 1
2) Balance H.
[tex]N_2H_{4\text{ }(g)}+2H_2O_{2\text{ }(g)}\rightarrow N_{2\text{ }(g)}+4H_2O_{(g)}[/tex]Reactants
N: 2
H: 8
O: 4
Products
N: 2
H: 8
O: 4
3) Balanced chemical equation.
[tex]N_2H_4+2H_2O_2\rightarrow N_2+4H_2O[/tex]The best coefficients are 1, 2, 1, and 4.
Option A.