Question

How many moles of O2 are required to react with 8.0 moles H2?

Answer 1

O2+ 2 H2 --> 2 H2O

x mol O2 - 8 mol H2
1 mol O2 - 2 mol H2


$x = \frac{1 \times 8}{2} = 4 \: mol$

answer: 4 moles