Distinction between pairs of compounds
Methylamine and methylethylamine.

Explanation

To distinguish between methylamine and methylethylamine, we can analyze their structural differences and their chemical properties. Here’s a step-by-step solution:

### Step 1: Identify the Structures
- **Methylamine (CH3NH2)**: This is a primary amine where one carbon atom is attached to the nitrogen atom.
- **Methylethylamine (C2H5NHCH3)**: This is a secondary amine where two carbon groups (methyl and ethyl) are attached to the nitrogen atom.

### Step 2: Classify the Amines
- **Methylamine**: Since it has one carbon group attached to the nitrogen, it is classified as a **primary amine**.
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