Which gas is primarily used in scuba tanks?

The primary gas used in scuba tanks is compressed air, which consists of approximately 78% nitrogen and 21% oxygen, with trace amounts of other gases. This composition closely mirrors the air we breathe at the surface, making it the most suitable choice for recreational diving. Compressed air provides divers with a breathable mixture that is safe to use at various depths, and it prevents issues such as oxygen toxicity, which can occur when breathing pure oxygen at significant depths.

Using air composed primarily of nitrogen and oxygen allows divers to experience the underwater environment safely and effectively. This gas mixture balances the need for breathable air while minimizing risks associated with other gases that could be harmful at depth.

While other options refer to gases that have specific uses in diving or for certain conditions, they do not serve as the standard for recreational scuba diving. For example, helium may be used in special gas mixtures for deep dives to mitigate the effects of narcosis, but it is not used as a primary dive gas for recreational purposes. Similarly, carbon dioxide is not used for breathing in scuba tanks and could create a deadly situation if it were. Pure oxygen has its applications in hyperbaric medicine and at shallow depths but is not suitable for breathing at recreational diving depths due to the risk