Question

A mixture of oxygen and ethyne(acetylene)is burnt for welding;can you tell why a mixture of ethyne and air is not used?​

Answer 1

Answer:

air mixed with other gases also so it is not used

Answer 2

HERE IS YOUR ANSWER MATE

When ethyne is burnt in air incomplete  supply oxygen present in the air.  However, if ethyne is burnt in oxygen, it gives a clean flame with high temperature (3000°C ) due to  complete combustion of ethyne.  Hence, this oxy-acetylene flame is used for welding and it is not possible to attain such a high  temperature with air. Due this reason a mixture of ethyne and air is not used for welding.