The type of case hardening using 50% charcoal, BaCO3, CaCO3 at a temperature close to 950 degrees is ________ carburising.

The type of case hardening using 50% charcoal, BaCO3, CaCO3 at a tempe

1.	The type of case hardening using 50% charcoal, BaCO3, CaCO3 at a temperature close to 950 degrees is ________ carburising.
A.	pack
B.	gas
C.	liquid
D.	liquid and gas
Answer» B. gas