In the extraction of `Al`, impure alumina is dissolved in conc. `NaOH` to form sodium to form sodium aluminate and leaving impurities behind. What is the name of this process ?

Explanation

To solve the question regarding the extraction of aluminum from impure alumina, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Process**: In the extraction of aluminum, impure alumina (Al₂O₃) is treated with concentrated sodium hydroxide (NaOH). This step is crucial as it allows for the separation of aluminum from its impurities.

2. **Chemical Reaction**: The chemical reaction that occurs when impure alumina is dissolved in concentrated NaOH can be represented as:
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