Iron pistons rings in a motor have 60 Co imbedded as a label with a concentration of 5.0 pCi/kg. The engine is lubricated by recirculation of 8 kg of oil. After 1.000 hours of operation, the oil is...

Iron pistons rings in a motor have
⁶⁰Co imbedded as a label with a concentration of 5.0 pCi/kg. The engine is lubricated by recirculation of 8 kg of oil. After 1.000 hours of operation, the oil is found to have a
⁶⁰Co concentration of 2.7 fCi/g. How much iron has been worn from the piston rings?