. A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

Solution: A mixture of oxygen and ethyne is burnt for welding instead of a mixture of ethyne and air because the production of heat is very important for welding metals. When oxygen and ethyne are burnt, it burns completely and produces a higher temperature than air and ethyne. Oxygen and ethyne produce a very hot blue flame, but the mixture of air and ethyne gives out a sooty flame which means that there are unburnt particles, resulting in lesser heat.