A student is provided with a white solid known to be either sodium oxide (Na2O\text{Na}_2\text{O}Na2O) or magnesium oxide (MgO\text{MgO}MgO).
Which procedure and observation would confirm that the solid is magnesium oxide?
Add a sample of the solid to distilled water, stir thoroughly, filter the mixture, and test the filtrate with pH indicator paper. The paper indicates a pH of approximately 13.
Add a sample of the solid to distilled water, stir thoroughly, filter the mixture, and test the filtrate with pH indicator paper. The paper indicates a pH of approximately 9.
Add a sample of the solid to an excess of dilute hydrochloric acid, stir thoroughly, filter the mixture, and test the filtrate with pH indicator paper. The paper indicates a pH of approximately 9.
Add a sample of the solid to an excess of dilute hydrochloric acid, stir thoroughly, filter the mixture, and test the filtrate with pH indicator paper. The paper indicates a pH of approximately 13.