Answer 2H2O2 ---> 2H2O + O2
The answer is balanced as it has
H- 4 H-4
O-4 O-4
To figure this out, you would have to first look at what you need
The H values already look balanced, so we will look at O
There are 2 on the reactant side and 3 on the product
Start by adding a 2 onto H2O2 (2H2O2)
We now have 4 H and 4 O values on that side, but we still need to change the products side
By adding a 2 to H2O, You would then have the number of required values.