Carboxylic acids are distinctly acidic and ionise in water to give `H_3 O^+` ions. In general, electron withdrawing groups increase the acidity of carboxylic acids while electron donating groups decrease the acidity of the carboxylic acid. The electron releasing groups such as` -CH_3 -OH, -NH_2` and `-OCH_3` make benzoic acid weaker while electron withdrawing groups such as `-CI, -NO_2`, etc., make benzoic acid stronger. The ortho isomer of every substituted benzoic acid is the strongest among the three isomers due to effect known as ortho effect. Carboxylic acids neutralise alkalies, decompose carbonates and bicarbonates evolving `CO_2 ` with brisk effervescence.
Give one test to distinguish between phenol and benzoic acid.

Explanation

To distinguish between phenol and benzoic acid, we can perform a simple test using sodium bicarbonate (NaHCO3). Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Prepare the Samples**: Take two separate test tubes. In one test tube, add a small amount of phenol, and in the other test tube, add a small amount of benzoic acid.

2. **Add Sodium Bicarbonate**: To both test tubes, add a few drops of sodium bicarbonate solution (NaHCO3).

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