A). if 3 mole of oxygen reacted, how many mole of iron (iii) oxide would be formed from the reaction?

If there is 3.0 moles of oxygen consumed, there is 2.0 mol of iron (III) oxide (Fe2O3) formed.

Explanation:

Step 1: Data given

Number of moles oxygen reacted = 3.0 moles

Step 2: The balanced equation

4Fe + 3O2 → 2Fe2O3

Step 3: Calculate moles of iron (III) oxide (Fe2O3)

For 4 moles Fe consumed, we need 3 moles of O2 to produce 2 moles of Fe2O3

For 3.0 moles O2 consumed , we need 2/3 * 3.0 = 2.0 moles of Fe2O3

If there is 3.0 moles of oxygen consumed, there is 2.0 mol of iron (III) oxide (Fe2O3) formed.