A 1-mm-thick BCC iron foil is used to separate a region of high nitrogen gas concentration of

Question:

A 1-mm-thick BCC iron foil is used to separate a region of high nitrogen gas concentration of 0.1 atomic percent from a region of low nitrogen gas concentration at 650 °C. If the flux of nitrogen through the foil is 1012 atoms / (cm2 · s), what is the nitrogen concentration in the low concentration region?