Answer:
1.2 moles
Explanation:
this is the balanced equation for the reaction of oxygen (O2) and hydrogen (H2), usually we don't write the 1 in front of O2
2H₂ + 10₂ → 2H₂O
the molar ratio of hydrogen to oxygen is 2 : 1
we are trying to react with 2.4 mol of H2 so the moles of O2 is half the number of moles of H2 = 2.4 ÷ 2 = 1.2 mol
another way to think of it:
2H₂ + 10₂
2 : 1
2.4 mol : x mol
to get from 2 to 2.4 multiply by 1.2, so do the same to the other side
1 × 1.2 = 1.2 mol