Select the odd out and justify your choice
`CaO, CuO, ZnO, FeO`

Explanation

To solve the problem of selecting the odd one out from the given oxides (CaO, CuO, ZnO, FeO), we will analyze the nature of each oxide.

### Step-by-Step Solution:

1. **Identify the Oxides**: The oxides given are:
- CaO (Calcium oxide)
- CuO (Copper(II) oxide)
- ZnO (Zinc oxide)
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