A mole is 6.023x10^23 of anything. So one mole of copper has 6.023x10^23 copper atoms. The only trick to these kinds of questions is when a question asks for the number of atoms in a mole of a compound containing that atom. So if we were talking about a mole of copper arsenate which is three copper atoms (well, ions) per two arsenate ions then the number of copper atoms is 3 x 6.023x10^23.