How many grams of oxygen gas will be produced if 289 g of NaClO3 is decomposed to sodium chloride and oxygen gas? (the fourth letter in this formula is not capital i, but a lower case l)

Answer 1

2NaClO3 ==> 2NaCl + 3O2
This is a simple stoichiometry problem. I went over this in detail for Veronica. Here is a link to that question. Post your work if you get stuck.
https://www.jiskha.com/questions/1815058/i-cant-get-this-if-4-00-g-of-h2-are-made-to-react-with-excess-co-g-how-many-grams-of