A sample of C₆₀ has 1 mass ppm of Fe impurity. When heated at 700 °C under pressure, C₆₀ is converted to a carbon polymer and iron to Fe₃C. Estimate the mass magnetization in J/(T kg) (≡ A m² /kg) of the product first magnetized and then taken to the Earth’s field. For Fe₃C, assume Mremanent = 700 kA/m and the density ρ = 7000 kg/m³.