Which one of the following is a redox reaction? O 2Na(g) + Cl2s) 2NACI(s) O NazCO,(s) + 2HC(aq) 2NAC(aq) + CO,(g)+ H,O) O Ba (aq) + SO (aq)BaSO ls) O K,Cr,0,laq) + 2KOH(ag) 2K,CrOlaq) + H2O O H2O)H'(aq) + OH (aq)