Which of the following gases are commonly used as inerting agents in welding processes?

The use of argon and helium as inerting agents in welding processes is primarily due to their chemical properties that prevent oxidation and contamination during the process. Inert gases do not react with the materials being welded, which is crucial in maintaining the purity of the weld and achieving a high-quality finish. Argon is the most commonly used inert gas in welding because it is readily available, cost-effective, and provides excellent shielding for a variety of welding techniques, including MIG (Metal Inert Gas) and TIG (Tungsten Inert Gas) welding. Helium, while more expensive, is used as well due to its ability to produce hotter arcs and improve penetration in certain welding applications, particularly when working with non-ferrous metals.

Options involving nitrogen and oxygen or carbon dioxide and hydrogen would not be suitable as inerting agents as they can react with the molten weld pool, leading to contamination, oxidation, or ineffective welds. Acetylene mixed with nitrogen is used primarily for cutting and brazing, rather than as an inerting agent, further underscoring why argon and helium are the preferred choices in welding contexts.