Ethyne (acetylene, \( C_2H_2 \)), a hydrocarbon, is employed in welding because of its high combustion temperature. Its luminous flame suits it for welding. Ethene (ethylene, \( C_2H_4 \)) and ethane (\( C_2H_6 \)) are not welding applications. Benzene, an aromatic compound, is also excluded from welding.