C. C and Pb; Carbon and Lead being in the same group.
Heat. When heat is appplied to liquid it turns into gas.
the process of changing one form of energy into another
Answer:
Never smoke near a place where hydrogen is generated or being used. Remove all possible sources of flame and sparks. Hydrogen should only be generated and used in a well ventilated out door area. Precautions must be taken to remove all possibilities of fire or explosion.