Calculate the change in oxidation state of the oxygen, on reaction with the following alkali metals on heating: (a) Li, (b) Na and (c ) Rb.

Explanation

To calculate the change in oxidation state of oxygen when it reacts with the alkali metals lithium (Li), sodium (Na), and rubidium (Rb) upon heating, we can follow these steps:

### Step 1: Reaction of Lithium with Oxygen
1. **Identify the product**: When lithium reacts with oxygen, it forms lithium oxide (Li₂O).
2. **Determine oxidation states**:
- Lithium (Li) has an oxidation state of +1.
- Let the oxidation state of oxygen in Li₂O be \( X \).
- The formula for the compound is:
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