The mass number is the sum of protons and neutrons. Since we have a mass number of 65, that means the sum of protons and neutrons add up to 65.
The number of neutrons given is 36. We can take the difference of the mass number and the number of neutrons to get the atomic number, or the number of protons.
65-36= 29 protons.
Since we got 29 protons, go to the periodic table of elements and find number 29 and you will get your element symbol. The symbol will be Cu, or Copper.
The question does not tell us that the copper has either a positive or negative charge. That will mean that the copper will be in its ground state. An atom in the ground state will have the same amount of electrons as the number of protons.
Therefore, the copper atom has 29 electrons.
The atomic number of selenium is 34. Since atomic number represents number of protons, that will be 34.
