Ca + H2S → CaS + H2 (Calcium reacts with hydrogen sulfide to form calcium sulfide and hydrogen gas)MnO2 + H2 → Mn + H2O (Manganese dioxide reacts with hydrogen gas to form manganese and water)H2 + P → PH3 (Hydrogen reacts with phosphorus to form phosphine)Sr + H3PO4 → Sr3(PO4)2 + H2 (Strontium reacts with phosphoric acid to form strontium phosphate and hydrogen gas)