How many coordination sites are there in ethylenediamine,
`{:(CH_2NH_2),(|),(CH_2NH_2):}`

Explanation

To determine the number of coordination sites in ethylenediamine (C2H8N2), we need to analyze its structure and the nature of the ligand.

### Step-by-Step Solution:

1. **Identify the Structure of Ethylenediamine**:
- Ethylenediamine consists of two amine groups (-NH2) attached to a two-carbon chain (ethylene). The structural formula can be represented as:
```
H2N-CH2-CH2-NH2
...