You need to learn how to determine this. Here is a set of rules that will allow you to determine the oxidation state of each element in each equation. Then you can answer the question.
http://www.chemteam.info/Redox/Redox-Rules.html
Which of the following equations does not represent an oxidation-reduction reaction?
3Al + 6HCl → 3H2 + AlCl3
2NaCl + Pb(NO3)2 → PbCl2 + 2NaNO3
2H2O → 2H2 + O2
2NaI + Br2 → 2NaBr + I2
Cu(NO3)2 + Zn → Zn(NO3)2 + Cu
2 answers
its the forth one