Which reagent is used to distinguish formic acid and acetic acid?

Explanation

To distinguish between formic acid and acetic acid, we can use the toluene reagent, which is ammonical silver nitrate (AgNO3 in ammonia solution).

### Step-by-Step Solution:

1. **Identify the Reagent**: The reagent used to distinguish between formic acid and acetic acid is ammonical silver nitrate (also known as Tollen's reagent).

2. **Reaction with Formic Acid**: When formic acid (HCOOH) is treated with ammonical silver nitrate, it reduces the silver ions (Ag+) to metallic silver (Ag), resulting in the formation of a silver mirror on the test tube. The reaction can be represented as:
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