`NH_(4)^(+)` ion in an aqueous solution will behave as :

Options

A. A base
B. An acid
C. Both acid and base
D. Neutral

Explanation

To determine how the ammonium ion (\(NH_4^+\)) behaves in an aqueous solution, we can follow these steps:

### Step 1: Identify the Nature of the Ion
The ammonium ion (\(NH_4^+\)) is a positively charged polyatomic ion formed by the protonation of ammonia (\(NH_3\)).

**Hint:** Remember that the charge of the ion and its formation from a base (ammonia) are key to understanding its behavior.

### Step 2: Understand the Acid-Base Properties
Ammonium ion can act as a weak acid. In an aqueous solution, it can donate a proton (\(H^+\)) to water, which results in the formation of ammonia and hydronium ions (\(H_3O^+\)).

**Hint:** Consider the definitions of acids and bases according to the Brønsted-Lowry theory, which states that acids donate protons and bases accept protons.

### Step 3: Analyze the pH Dependence
The behavior of the ammonium ion is influenced by the pH of the solution. In a low pH environment (acidic), the equilibrium shifts to the right, favoring the formation of more ammonium ions from ammonia. Conversely, in a high pH environment (basic), the equilibrium shifts to the left, favoring the formation of ammonia from ammonium ions.

**Hint:** Think about how the concentration of \(H^+\) ions in the solution affects the equilibrium between \(NH_3\) and \(NH_4^+\).

### Step 4: Conclude the Behavior of \(NH_4^+\)
Since the ammonium ion can donate protons in an aqueous solution, it behaves as an acid. Therefore, the correct answer to the question is that the ammonium ion behaves as an acid in an aqueous solution.

**Hint:** Look for the ability of the ion to donate protons as a key indicator of its acidic behavior.

### Final Answer:
The ammonium ion (\(NH_4^+\)) in an aqueous solution behaves as an acid.