If 84.9 grams of solid iron reacts with oxygen gas, how many molecules of oxygen will react

Molecules of oxygen

Explanation:

The balanced equation of reaction between iron and oxygen is  

4 Fe     +  3 O2  → 2 Fe2O3

4 moles of iron react with 3 moles of oxygen.

Mass of one mole of iron is 55.845

number of iron moles in 84.9 grams of solid iron is equal to

Now 1 mole of iron will react with mole of oxygen

Thus 1.52 moles of iron will react with moles of oxygen

Number of atoms of oxygen in 1.14 moles