1. Name all the elements so far studied which possess allotropic forms.
2. What compounds would you expect phosphorus to form with bromine and iodine? Write the equations showing the action of water on these compounds.
3. In the preparation of phosphine, why is coal gas passed into the flask? What other gases would serve the same purpose?
4. Give the formula for the salt which phosphine forms with hydriodic acid. Give the name of the compound.
5. Could phosphoric acid be substituted for sulphuric acid in the preparation of the common acids?
6. Write the equations for the preparation of the three sodium salts of orthophosphoric acid.
7. Why does a solution of disodium hydrogen phosphate react alkaline?
8. On the supposition that bone ash is pure calcium phosphate, what weight of it would be required in the preparation of 1 kg. of phosphorus?
9. If arsenopyrite is heated in a current of air, what products are formed?
10. (a) Write equations for the complete combustion of hydrosulphuric acid, methane, and arsine. (b) In what respects are the reactions similar?