Find out whether or not each reaction is a redox reaction. For those reactions that are redox reactions, recognize the substance being oxidized and the substance being reduced.
a. Zn(s) + CoCl2(aq) - ZnCl2(aq) + Co(s)
b. HI(aq) + NaOH(aq) - H2O(l) + NaI(aq)
c. AgNO3(aq) + NaCl(aq) - AgCl(s) + NaNO3(aq)
d. 2 K(s) + Br2(l) - 2KBr(s)