How many grams of NH4ClO4 would dissolve in 250 mL at 30 C

Ammonium perchlorate appears as a white, crystalline solid or powder. Classified as a division 1.1 explosive if powdered into particles smaller than 15 microns in diameter or if powdered into larger particles but thoroughly dried. Does not readily burn, but will burn if contaminated by combustible material. May explode under prolonged exposure to heat or fire. Used to make rocket propellants, explosives, pyrotechnics, as an etching and engraving agent, and in analytical chemistry.

Yes it would be a physical change.