The chemical equation below represents an acid-base reaction.

NO2-(aq) + H2O(l) → HNO2(aq) + OH-(aq)

The NO2-(aq) acts as
A.
a Bronsted base.

B.
an Arrhenius acid.

C.
a Bronsted acid.

D.
an Arrhenius base.

D. an Arrhenius base.

In the given chemical equation, NO2-(aq) reacts with H2O(l) to form HNO2(aq) and OH-(aq). To determine the role of NO2-(aq), we need to understand the definitions of Bronsted and Arrhenius acids and bases.

According to the Bronsted-Lowry definition, an acid is a substance that donates a proton (H+), while a base is a substance that accepts a proton.

In the given equation, NO2-(aq) accepts a proton (H+) from H2O(l) to form HNO2(aq). Therefore, NO2-(aq) acts as a base (accepts a proton).

So, the correct answer is A. a Bronsted base.

To determine the role of NO2-(aq) in the given chemical equation, we need to understand the definitions of Bronsted acids and bases as well as Arrhenius acids and bases.

1. Bronsted acid/base: According to the Bronsted-Lowry acid-base theory, an acid is a substance that donates a proton (H+), while a base is a substance that accepts a proton.

2. Arrhenius acid/base: According to the Arrhenius acid-base theory, an acid is a substance that produces H+ ions in aqueous solution, while a base is a substance that produces OH- ions in aqueous solution.

Now, let's analyze the given chemical equation:
NO2-(aq) + H2O(l) → HNO2(aq) + OH-(aq)

In this reaction, we can observe that NO2-(aq) accepts a proton (H+) from H2O, resulting in the formation of HNO2(aq). This indicates that NO2-(aq) is acting as a base because it accepts a proton.

Therefore, the correct answer is:
A. a Bronsted base.