A student was asked to prepare oxygen from `KClO_(3)` in the laboratory. After th experiment was over, he put the burner off immediately. What do you think happened then?

Explanation

### Step-by-Step Solution:

1. **Understanding the Reaction**: The student is tasked with preparing oxygen gas (O₂) from potassium chlorate (KClO₃). The process involves heating KClO₃, which undergoes thermal decomposition.

2. **Thermal Decomposition of KClO₃**: When KClO₃ is heated, it decomposes into potassium chloride (KCl) and oxygen gas (O₂). The balanced chemical equation for this reaction is:
\[ 2 \text{KClO}_3 \rightarrow 2 \text{KCl} + 3 \text{O}_2 \]
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