Purification of copper can be achieved by electrorefining copper from an impure copper anode onto a pure copper cathode in an electrolytic cell. How many hours will it take to plate 18.0 kg of copper onto the cathode if the current passed through the cell is held constant at 31.0 A? Assume the copper in the electrolytic solution is present as Cu2 .

a. patterns can explain observations.

i'm assuming that the correct answer is indeed the first one/ "a"..

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

the answer is barium and copper bromide