1. Assign Oxidation Numbers:
* Na (sodium): Starts as 0 (elemental state) and ends as +1 in NaOH.
* H (hydrogen): Starts as +1 in H₂O and ends as 0 in H₂.
* O (oxygen): Starts as -2 in H₂O and ends as -2 in NaOH.
2. Identify the Change:
* Sodium (Na) increases its oxidation number from 0 to +1.
* Hydrogen (H) decreases its oxidation number from +1 to 0.
* Oxygen (O) remains the same.
Conclusion:
The element that increases its oxidation number in the reaction is sodium (Na).
