Which heat-treating operation would be performed when the surface of the metal is changed chemically by introducing a high carbide or nitride content?

Case-hardening

Explanation:

Case-hardening

It is the process of hardening the surface of the metal object and allowing the metal which is deep inside to remain soft , hence , making a thin hard outer layer on the surface .

In case of iron which have low carbon content , the case - hardening is done by introducing high carbide or nitride content .

The process of case - hardening is done , in the final shaping process .

the answer is na (sodium)

56 moles of   lieter in chemistry