Context: Hydrogen gas (dihydrogen or molecular hydrogen) is highly flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion for hydrogen is −286 kJ/mol:

Question: For hydrogen what is the enthalpy of combustion?
Answer: 286 kJ/mol

Question: What are two forms of hydrogen gas?
Answer: dihydrogen or molecular hydrogen

Question: Which element has a enthalpy of combustion at −286 kJ/mol?
Answer: Hydrogen