When a metal is placed in an ionic solution, a redox reaction can occur and the metal dissolves. In which of the following cases will such a reaction occur? We assume we have standard conditions. Use the voltage series (standard reduction potentials) to find the solution to the problem. One of the answers below are correct.

a) Copper, Cu (s) in a 1 molar solution of zinc sulphate, ZnSO₄

b) Silver, Ag (s) in a 1 molar HCl solution

c) Copper, Cu (s) in a 1 molar HNO₃-solution

d) Gold, Au (s) in a 1 molar HNO₃-solution