Which of the following reactions are not possible ?

Question

$\begin{array}{1 1}(a)\;Cl_2+KBr\rightarrow KCl+Br_2\\(b)\;Br_2+KI\rightarrow KBr+I_2\\(c)\;Zn+H^+\rightarrow Zn^{+2}+H_2\\(d)\;Cu+H^+\rightarrow Cu^{+2}+H_2\end{array}$