An aqueous solution of hydrazine (N₂H₄) is electrochemically oxidized by O₂, thereby releasing chemical energy in the form of electrical energy. One of the products generated from the electrochemical reaction is N₂(g).

Choose the correct statement(s) about the above process

The correct statements are:
1. OH⁻ ions react with N₂H₄ at the anode to form N₂(g) and water, releasing 4 electrons to the anode.
2. At the cathode, molecular oxygen gets converted to OH⁻

Explanation:
In a hydrazine-oxygen (N₂H₄ - O₂) fuel cell operating in an alkaline medium, the electrochemical processes occurring at the electrodes are as follows:

1. Anodic Process (Oxidation):
At the anode, hydrazine (N₂H₄) undergoes oxidation. It reacts with hydroxide ions (OH⁻) present in the alkaline electrolyte to produce nitrogen gas (N₂) and water, releasing four electrons to the anode.
The balanced half-reaction at the anode is:
$N_2{H}_4\left(\mathrm{aq}\right)+4{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)\to N_2\left(g\right)+4H_{2}O\left(l\right)+4e^{-}$
This confirms the first statement is correct.

2. Cathodic Process (Reduction):
At the cathode, molecular oxygen (O₂) undergoes reduction. It accepts the electrons coming from the anode through the external circuit and reacts with water to form hydroxide (OH⁻) ions.
The balanced half-reaction at the cathode is:
$O_2\left(g\right)+2H_{2}O\left(l\right)+4e^{-}\to 4{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)$
This confirms that molecular oxygen gets converted to OH⁻ at the cathode, making the second statement correct.

Overall Cell Reaction:
Combining the anode and cathode half-reactions gives:
$N_2{H}_4\left(\mathrm{aq}\right)+O_2\left(g\right)\to N_2\left(g\right)+2H_{2}O\left(l\right)$
Since the only products of this clean electrochemical process are nitrogen gas (N₂) and water (H₂O), no harmful oxides of nitrogen (NO_x) are produced as major by-products.