Final answer:
There are 74.4 moles of O in 12.4 mol Fe(NO3)2.
Step-by-step explanation:
Based on the chemical formula Fe(NO3)2, there are 2 moles of NO3 per 1 mole of Fe(NO3)2. In one mole of NO3, there are 3 moles of O. Therefore, in 12.4 moles of Fe(NO3)2, there would be 12.4 x 2 x 3 = 74.4 moles of O.
Learn more about Moles of O in a compound