Which of the following are redox reactions?

(a) Ba(NO3)2 (aq) + H2SO4 (aq) -> BaSO4 (s) + 2 HNO3 (aq)

(b) NH4NO2 (s) -> N2 (g) + 2 H2O (g)

(c) CuO (s) + H2 (g) -> Cu (s) + H2O (L)

How can you tell? Look at the oxidation state of the elements and compare oxidn state on the left with the oxdn state on the right. If they change it is a redox equation. If not it is not a redox equation. I'll do the first one.

Ba is +2 to +2
N is +5 to +5
O is -2 to -2
H is +1 to +1
S is +6 to +6
So nothing changed which makes a) not a redox. Here is a site that will help you assign oxidation states to the elements.
http://www.chemteam.info/Redox/Redox-Rules.html

Well, let's "redox" our brain cells for a moment!

(a) Ba(NO3)2 (aq) + H2SO4 (aq) -> BaSO4 (s) + 2 HNO3 (aq)

Hmm... I see some NO3 going from one side to the other, but I don't see any changes in oxidation states. So, this one is not a redox reaction. It's just a plain old precipitation reaction.

(b) NH4NO2 (s) -> N2 (g) + 2 H2O (g)

Now we're talking! The nitrogen in NH4NO2 goes from an oxidation state of +1 to 0 in N2. So, this one is indeed a redox reaction. It's like the nitrogen got a makeover!

(c) CuO (s) + H2 (g) -> Cu (s) + H2O (L)

Oh, copper! You never fail to create a reaction! In this case, the copper in CuO goes from an oxidation state of +2 to 0 in Cu. That means we have ourselves another redox reaction!

So, in summary, option (b) and option (c) are the redox reactions. Keep up the good work, my curious friend!

To determine which of the given reactions are redox reactions, we need to examine the changes in oxidation states of the elements involved in each reaction.

(a) Ba(NO3)2 (aq) + H2SO4 (aq) -> BaSO4 (s) + 2 HNO3 (aq)
In this reaction, the oxidation states of the elements do not change. Ba has an oxidation state of +2, N in NO3 has an oxidation state of +5, S in H2SO4 has an oxidation state of +6, and H in HNO3 has an oxidation state of +1. Since there is no change in oxidation states, this is not a redox reaction.

(b) NH4NO2 (s) -> N2 (g) + 2 H2O (g)
In this reaction, the nitrogen in NH4NO2 changes from an oxidation state of +3 to 0 in N2. Since the oxidation state of nitrogen changes, this reaction is a redox reaction.

(c) CuO (s) + H2 (g) -> Cu (s) + H2O (L)
In this reaction, the oxidation state of copper changes from +2 in CuO to 0 in Cu. The hydrogen in H2 changes from an oxidation state of 0 to +1 in H2O. Both copper and hydrogen undergo changes in oxidation states, so this reaction is also a redox reaction.

So, the correct options are (b) and (c).

To determine which of the given reactions are redox reactions, we need to check if there is a transfer of electrons between the reactants.

In a redox reaction, there is oxidation (loss of electrons) and reduction (gain of electrons) occurring simultaneously. One way to identify redox reactions is to look for changes in oxidation states.

Let's examine each of the given reactions:

(a) Ba(NO3)2 (aq) + H2SO4 (aq) -> BaSO4 (s) + 2 HNO3 (aq)
There is no change in oxidation state for any of the elements in this reaction. Barium (Ba) has an oxidation state of +2 on both sides of the reaction, and nitrogen (N), sulfur (S), and hydrogen (H) also have the same oxidation states. Therefore, reaction (a) is not a redox reaction.

(b) NH4NO2 (s) -> N2 (g) + 2 H2O (g)
In this reaction, the nitrogen (N) in NH4NO2 goes from an oxidation state of +1 to 0 in N2. The nitrogen is gaining electrons, which means it is being reduced. Therefore, reaction (b) is a redox reaction.

(c) CuO (s) + H2 (g) -> Cu (s) + H2O (L)
In this reaction, the copper (Cu) in CuO goes from an oxidation state of +2 to 0 in Cu. The copper is gaining electrons, which means it is being reduced. Therefore, reaction (c) is a redox reaction.

To summarize, reactions (b) and (c) are redox reactions as there is a change in the oxidation states of the elements involved.