Which of the following gases is commonly used in air compressors?

The correct answer is nitrogen, which is commonly used in air compressors for various applications. Nitrogen is an inert gas that does not support combustion, making it a safe choice for many industrial processes. It is also readily available and can be produced in large quantities, providing an efficient and cost-effective option for pressurizing systems.

In the context of air compressors, nitrogen is often utilized in applications where moisture and oxygen need to be minimized, as it helps maintain the quality and integrity of the compressed air. This is particularly important in environments sensitive to oxidation or where the presence of moisture could lead to corrosion or other issues.

The other gases listed, while they have specific applications, are not typically used in standard air compression practices. Oxygen, for instance, supports combustion and poses a safety risk in compressed air systems. Helium, while used in specialized applications like cooling and lightweight lifting, is not commonly employed in air compressors due to its high cost and limited availability. Hydrogen, despite its energy properties, is also not used in air compressors because it is highly flammable and poses significant safety hazards when compressed.