You have 2 atoms of O on the left while you have one on the right side of the equation. Correct that as below
Now oxygen molecule is balanced. Take hydrogen. 2 atoms on the left side. We have 4 on the other. Balance this.
Now all the elements are balanced in the equation.
As per this equation 2 moles of
1 gmole of
10 g of
If we have
Molecular weight of water
Otherwise the product formed is a function of