Argon and helium are categorized as:

Argon and helium are categorized as:

• A. reactive gases.
• B. inert gases.
• C. ionized gases.
• D. non-conductive gases.

Answer: (B)

Noble gases have full outer electron shells, which makes them very unreactive. Because their valence shell is complete, they don’t readily gain, lose, or share electrons, so they don’t form bonds under normal conditions. That chemical stability is exactly what “inert gases” means. In welding, this inertness is useful because argon and helium can blanket the weld without reacting with the molten metal or atmospheric gases, protecting the weld pool. The other descriptions don’t capture this key point: they aren’t reactive by definition, they aren’t typically ionized in everyday contexts, and while they are insulating gases, their defining classification in this context is their chemical inertness.

Noble gases have full outer electron shells, which makes them very unreactive. Because their valence shell is complete, they don’t readily gain, lose, or share electrons, so they don’t form bonds under normal conditions. That chemical stability is exactly what “inert gases” means. In welding, this inertness is useful because argon and helium can blanket the weld without reacting with the molten metal or atmospheric gases, protecting the weld pool. The other descriptions don’t capture this key point: they aren’t reactive by definition, they aren’t typically ionized in everyday contexts, and while they are insulating gases, their defining classification in this context is their chemical inertness.