3. Balance the following Oxidation-Reduction equations: (10%)a. ____ PbS(s) + ____ O2 (g)  ____ PbO (s) + ____ SO2(g)b. ____ H+(aq)+ ____Cr2O72- (aq) + ____ C2H5OH (l) ____ Cr3+(aq)+ ____ H2O (l)+____CO2(g)