` pK_a` value of m-hydroxybenzoic acid is less / more than that of benzoic acid.

Explanation

To determine whether the pKa value of m-hydroxybenzoic acid is less than or more than that of benzoic acid, we can follow these steps:

### Step 1: Understand the Concept of Acidity
Acidity is defined by the ability of a substance to donate protons (H+ ions). The strength of an acid is often measured by its dissociation constant (Ka). A higher Ka value indicates a stronger acid, while a lower Ka value indicates a weaker acid.

**Hint:** Remember that stronger acids have lower pKa values because pKa is the negative logarithm of Ka.

### Step 2: Define pKa
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