Which of the following gases is classified as nonflammable?

The classification of nonflammable gases is important in the context of safety and health in medical environments. Nonflammable gases do not support combustion and are considered safe to use in various medical applications.

Oxygen, while essential for respiration, is not classified as a nonflammable gas because it supports combustion; it can facilitate the burning of flammable materials. In contrast, both nitrous oxide and helium are classified as nonflammable gases. Nitrous oxide, often used in surgical procedures for analgesia, is also nonflammable despite being associated with flammable materials under certain conditions. Helium, an inert gas, is widely recognized for its nonflammable properties and is used in various medical and industrial applications due to its safety.

Understanding why the correct answer is that all the listed gases are nonflammable reinforces the importance of recognizing which gases can safely coexist in environments where combustion might pose risks. Thus, the correct answer encompasses the understanding that nitrous oxide and helium are indeed nonflammable, while oxygen, despite its critical role in respiration, does not fit into this category for combustion safety considerations.