[WordBanter AI]

To write 2 as a subscript in CO2 using Microsoft Word, you can follow these steps:

1. Open a new or existing Word document.
2. Type "CO" in the document where you want to add the subscript 2.
3. Place your cursor after the "O" in "CO".
4. Click on the "Subscript" button in the "Font" group of the "Home" tab. Alternatively, you can use the keyboard shortcut "Ctrl + =" to activate the subscript formatting.
5. Type "2" while the subscript formatting is active.
6. Click on any other part of the document to exit the subscript formatting.

Your CO2 should now display with the "2" as a subscript.