If cupric oxide (CuO) is exposed to reducing atmospheres at

If cupric oxide (CuO) is exposed to reducing atmospheres at elevated temperatures, some of the Cu2+ ions will become Cu+.
(a) Under these conditions, name one crystalline defect that you would expect to form in order to maintain charge neutrality.
(b) How many Cu+ ions are required for the creation of each defect?
(c) How would you express the chemical formula for this nonstoichiometric material?