| 423 / | HD | CHEMISTRY OF INORGANIC COMPOUNDS |
| 462 | DF | HALOGEN OR COMPOUND THEREOF {10} |
| 481 | | .~ Hydrogen halide {4} |
| 482 | DF | .~.~> By reacting alkali metal salt with sulfuric acid |
| 483 | DF | .~.~> Hydrogen fluoride {1} |
| 486 | DF | .~.~> Utilizing an element as reactant {1} |
| 488 | DF | .~.~> Recovery or purification |