What do you think would be the observation if the a-particle scattering experiment is carried out using a foil of a metal other than gold?

On using any other metal other than gold would not have affected the observations of the experiment. Since, the structure of an atom is same for all states of atom. All other metals are not as ductile as gold, so a thin foil would have been difficult to obtain. If a thick foil is used in this experiment, then more alpha particles would have bounced back. As a result, no idea about the location of nucleus and the presence of empty space in an atom would be available with such a certainty.