Which one of the following is not a redox reaction?

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)

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

Thank you so much!

The reaction 2H2O(g) -> 2H2(g) + O2(g) is not a redox reaction. In this reaction, water molecules are decomposed into hydrogen gas (H2) and oxygen gas (O2), but there is no change in the oxidation numbers of the elements.

To determine which of the given reactions is not a redox reaction, we need to understand the concept of redox reactions.

A redox reaction involves the transfer of electrons between two or more species. In these reactions, one species undergoes reduction (gains electrons) while another species undergoes oxidation (loses electrons). The reactant that undergoes reduction is called the oxidizing agent, while the reactant that undergoes oxidation is called the reducing agent.

Let's analyze each given reaction to identify if they involve the transfer of electrons:

1. PbO2(s) + Pb(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l)
In this reaction, lead (Pb) in PbO2 is reduced from a higher oxidation state (+4) to a lower oxidation state (+2) while lead (Pb) in Pb undergoes oxidation from a lower oxidation state (+0) to a higher oxidation state (+2). Therefore, this reaction is a redox reaction.

2. Ba(NO3)2(aq) + Na2CrO4(aq) → BaCrO4(s) + 2NaNO3(aq)
In this reaction, there is no change in oxidation states for any of the elements involved. Ba, Na, Cr, and O maintain their original oxidation states throughout the reaction. Therefore, this reaction is not a redox reaction.

3. Zn(s) + 2MnO2(s) → ZnO(s) + Mn2O3(s)
In this reaction, zinc (Zn) is oxidized from an oxidation state of 0 to +2, and manganese (Mn) in MnO2 is reduced from an oxidation state of +4 to +3. Therefore, this reaction is a redox reaction.

4. 2H2O(g) → 2H2(g) + O2(g)
In this reaction, hydrogen (H) in water (H2O) is reduced from an oxidation state of +1 to 0 in H2(g), whereas oxygen (O) in H2O is oxidized from -2 to 0 in O2(g). Therefore, this reaction is a redox reaction.

Based on the analysis, the reaction that is not a redox reaction is:

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