If you were plating with copper, which electrolyte could be used

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

How air particles exert a pressure on the inside of the balloon

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.