Which metal oxide decomposes upon heating?

In the reaction $Cu_{(s)} + 2Ag^{+}_{(aq)} \to Cu^{2+}_{(aq)} + 2Ag_{(s)}$,the reduction half-cell reaction is:

Which of the following statements are true for fuel cells?

The reaction $\frac{1}{2} H_{2(g)} + AgCl_{(s)} \rightarrow H^+_{(aq)} + Cl^-_{(aq)} + Ag_{(s)}$ occurs in which of the following galvanic cells?

At the anode,the process of $......$ occurs,and at the cathode,the process of $......$ occurs.

In a hydrogen-oxygen fuel cell,the combustion of hydrogen occurs to: