This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
The purpose of heating gold foil before condensing is: 
Select and explain. 
A. To improve welding quality, B. To melt the gold, C. To remove adsorbed gases on gold surface, D. To increase oxidation
C: To remove adsorbed gases on gold surface
Answer: C: To remove adsorbed gases on gold surface 
Explanation: Gold attracts gases that render it noncohesive, such gases must be removed from the surface of the gold before dental compaction. This process is usually referred to as degassing or annealing and is accomplished by application of heat.