Give one example of a combination reaction which is also exothermic.

Explanation

### Step-by-Step Solution:

1. **Understand the Definitions**:
- A **combination reaction** is a type of chemical reaction where two or more reactants combine to form a single product.
- An **exothermic reaction** is a reaction that releases heat energy to the surroundings.

2. **Identify an Example**:
- We need to find a reaction that fits both definitions: it must be a combination reaction and also exothermic.
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