Balance the following oxidation-reduction reactions that occur in basic solution. (Use the lowest possible coefficients.)
(a) H2O(l) + Cr(s) + CrO42-(aq) Cr(OH)3(s) + OH -(aq)
(b) H2O(l) + S2-(aq) + MnO4-(aq) S(s) + MnS(s) + OH -(aq)
(c) H2O(l) + CN-(aq) + MnO4-(aq) CNO-(aq) + MnO2(s) + OH -(aq)