PAN are formed by the combination of aldehydes with ...............and oxides of ..........in the presence of sunlight .

Explanation

To solve the question: "PAN are formed by the combination of aldehydes with ...............and oxides of ..........in the presence of sunlight", we need to identify the correct substances that react with aldehydes to form PAN (Peroxyacetyl Nitrate).

### Step-by-Step Solution:

1. **Identify the Reactants**:
- PAN is formed from the reaction of aldehydes. The question hints at two reactants: one that combines with aldehydes and another that is an oxide.

2. **First Reactant - Ozone**:
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