Which one of the following is not a redox reaction?

Question

PbO2(s) + Pb(s) + 2H2SO4(aq) 2PbSO4(s) + 2H2O(l)

Ba(NO3)2(aq) + Na2CrO4(aq) BaCrO4(s) + 2NaNO3(aq)

Zn(s) + 2MnO2(s) ZnO(s) + Mn2O3(s)

2H2O(g) 2H2(g) + O2(g)

Answer 1

lol I think you forgot to put the arrow symbol somewhere in those reactions. But it can still be answered.

The answer is
Ba(NO3)2(aq) + Na2CrO4(aq) -> BaCrO4(s) + 2NaNO3(aq)
This is just a double displacement reaction. And looking at the charge of each element involved (in reactant and product side), the charges of the individual elements did not change, thus making it not a redox reaction.

Hope this helps :3

Answer 2

Thank you so much!