GED Science TestPhysical ScienceEasy
A technician is preparing to weld two metal pieces together. They need to select a gas that will protect the molten metal from reacting with atmospheric oxygen and nitrogen. Which property of a gas is most important for this application?
- AHigh specific heat
- BLow density
- CChemical inertness
- DHigh thermal conductivity
Show answer & explanationAnswer & explanation
Correct answer: C. Chemical inertness
For welding, the primary goal of the shielding gas is to prevent unwanted chemical reactions with the atmosphere. This requires a gas that is chemically unreactive, or inert. Argon is a common inert gas used for this purpose.
Why the other options are wrong
- A. High specific heat is related to how much energy a substance can absorb, not its chemical reactivity.
- B. Low density might affect gas flow but is not the main property for chemical protection.
- D. High thermal conductivity is not the primary requirement for a shielding gas; it's about preventing chemical reactions.
Chemical Inertness
Chemical inertness is the property of a substance that describes its lack of reactivity with other chemical substances.
- Inert substances do not readily undergo chemical reactions.
- Noble gases are well-known for their chemical inertness.
- This property is useful in applications requiring protection from chemical change.
Memory trick: Shielding gas must be the 'Silent Guardian' of the weld.