Final answer:
The isotope with 29 protons and 56 neutrons is Cu-85, a positively charged copper ion with a mass number of 85 and a charge of +9, due to having 20 electrons. Cu-85 is not a naturally occurring or stable isotope of copper.
Step-by-step explanation:
The isotope with 29 protons is copper (Cu) because the atomic number, which is equal to the number of protons, defines the element. Since the atom has 29 protons and 20 electrons, it means it is positively charged with a charge of +9 (29 - 20), indicating that this is a copper ion, not a neutral atom. As for the neutrons, if an isotope has 56 neutrons and 29 protons, its mass number would be the sum of protons and neutrons, giving us 85 (29 + 56). Therefore, the isotope in question is Cu-85, which is not a naturally occurring or stable isotope of copper. Copper usually has isotopes with a mass number of 63 (Cu-63) and 65 (Cu-65).