Arrange the following sets in order of their basic strength:
Ethylamine, ammonia and triethylamine.

Explanation

To determine the order of basic strength among ethylamine, ammonia, and triethylamine, we need to analyze the structures and the influence of substituents on the nitrogen atom in each compound. Here’s a step-by-step solution:

### Step 1: Understand Basic Strength
Basic strength refers to the ability of a compound to donate a lone pair of electrons. The more readily a compound can donate its lone pair, the stronger the base it is.

### Step 2: Analyze the Structures
1. **Ammonia (NH₃)**:
- Structure: H₃N
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