(a) Calculate the fraction of atom sites that are vacant for copper (Cu) at a temperature of 485C (758 K). Assume an energy for vacancy formation of 0.90 eV/atom. i 13.77 (b) Repeat this calculation at room temperature (298 K). 6.08e-16 (c) What is ratio of N/N(758 K) and N/N (298 K)? i 1.021e10 For a BCC iron-carbon alloy that contains 0.17 wt% C, calculate the fraction of unit cells that contain carbon atoms. One carbon atom per i unit cells.