it depends on what kind of reaction it is. it could be 10 moles too, but it can be less, for example, if the products looked like this
CO2+2 H2O the answer would be:
x mol CO2 - 10 mol H20
1 mol CO2 - 2 mol H2O
[tex]x = \frac{1 \times 10}{2} = 5 \: mol[/tex]
