Indicate which reactions are redox reactions. Cd(s) Pb2 (aq)→Cd2 (aq) Pb(s) Si(s) O2(g)→SiO2(s) 2Li(s) Cl2(g)→2LiCl(s) Pb(NO3)2(aq) 2LiCl(aq)→PbCl2(s) 2LiNO3(aq)