contestada

Which of the following is an oxidation-reduction reaction?
ZnS(s) + 2O2(g) Right arrow. ZnSO4(s)
CaO(s) + H2O(l) Right arrow. Ca(OH)2(s)
6Li2O(s) + P4O10(g) Right arrow. 4Li3PO4(s)
SO2(g) + H2O(l) Right arrow. H2SO3(aq)