An isotope contains 56 protons, 54 electrons, and 74 neutrons. What is the identity of the isotope?

answer is 130barium+2

Answer is: this is isotope of barium, because barium has atomic number 56 (number of protons), mass number of this isotope of barium is 130 (56 protons + 76 neutrons). This isotope is cation with oxidation number + 2, because barium has two protons more than electrons (56 - 54 = 2).