Since CuO has one atom of copper in it, the theoretical relationship between moles of copper and moles of copper oxide is 1:1. You will have .008 moles of copper oxide if you oxidize all of .008 moles of copper.
What Is The Expected/theoretical Number Of Moles Of Copper Oxide CuO Of The Starting # Of Cu Moles Was .008 And .509 G/ Ending With A Gain On Mass Of CuO Of .128g?