`pK_(a)` value of 4-nitrobenzoic acid is lower than that of benzoic acid. Why ?

Explanation

To understand why the pKa value of 4-nitrobenzoic acid is lower than that of benzoic acid, we can break down the explanation into a series of steps:

### Step 1: Understand the Structures
- **4-Nitrobenzoic Acid**: This compound has a carboxylic acid group (-COOH) and a nitro group (-NO2) attached to a benzene ring. The nitro group is located at the para position relative to the carboxylic acid group.
- **Benzoic Acid**: This compound has only the carboxylic acid group attached to the benzene ring without any substituents.

### Step 2: Define pKa
- The pKa value is a measure of the acidity of a compound. A lower pKa value indicates a stronger acid, meaning it more readily donates protons (H⁺ ions).
...