The magnetic moment of the Earth is approximately $8.00 \times 10^{22} \mathrm{~A} \cdot \mathrm{m}^{2}$
(a) Imagine that the planetary magnetic field were caused by the complete magnetization of a huge iron deposit. How many unpaired electrons would participate? (b) At two unpaired electrons per iron atom, how many kilograms of iron would compose the deposit? Iron has a density of $7900 \mathrm{~kg} / \mathrm{m}^{3}$ and approximately $8.50 \times 10^{28}$ iron atoms $/ \mathrm{m}^{3}$