Question

unsaturated hydrocarbon used for welding purposes

Answer 1

Ethylene-- is unsaturated hydrocarbon used for welding purposes .

Answer 2

Hydrocarbons are excellent fuel materials which are vastly used for metal welding purposes.

Similarly, acetylene is one of the most common hydrocarbons which is used for modern day metal welding.

And acetylene is itself an unsaturated hydrocarbon.

(Basically we use a mixture of acetylene and oxygen for the metal welding)