Which allotropic form of oxygen is unstable?

Explanation

To determine which allotropic form of oxygen is unstable, we need to analyze the two known allotropes of oxygen: O2 (dioxygen) and O3 (ozone).

### Step-by-Step Solution:

1. **Identify the Allotropes of Oxygen**:
- Oxygen exists in two primary allotropic forms: O2 and O3.
- O2 is commonly known as dioxygen, while O3 is known as ozone.

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