Arrange the following in increasing order of their basic strength :
`C_2 H_5 NH_2 ,(C_2H_5)_2 NH, (C_2 H_5)_3 N, C_5 H_5 NH_2`

Explanation

To arrange the compounds \( C_2H_5NH_2 \) (ethylamine), \( (C_2H_5)_2NH \) (diethylamine), \( (C_2H_5)_3N \) (triethylamine), and \( C_5H_5NH_2 \) (aniline) in increasing order of their basic strength, we can follow these steps:

### Step 1: Understand the Structure of Each Compound
1. **Ethylamine (\( C_2H_5NH_2 \))**: This is a primary amine with one ethyl group attached to the nitrogen.
2. **Diethylamine (\( (C_2H_5)_2NH \))**: This is a secondary amine with two ethyl groups attached to the nitrogen.
3. **Triethylamine (\( (C_2H_5)_3N \))**: This is a tertiary amine with three ethyl groups attached to the nitrogen.
4. **Aniline (\( C_5H_5NH_2 \))**: This is an aromatic amine where the nitrogen is attached to a benzene ring.

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