Dropping phosphoric acid into sodium silicate solution to precipitate silicic acid shows that phosphoric acid is more acidic than silicic acid and phosphorus is more nonmetallic than silicon.

The dilute solution of phosphoric acid and sulfuric acid was prepared with equimolar hydrogen ions, and its pH value was determined by pH test paper. It is found that the acidity of sulfuric acid solution is stronger than that of phosphoric acid with the same concentration, indicating that sulfur is more nonmetallic than phosphorus.