Certified Hyperbaric Technologist Practice Test 2026 – Comprehensive Exam Prep

The correct choice highlights that the primary components of gases in Earth's atmosphere are indeed predominantly composed of nitrogen and oxygen. Specifically, nitrogen makes up about 78% of the atmosphere, while oxygen constitutes roughly 21%. This balance is critical for maintaining life on Earth, as nitrogen is an inert gas that helps stabilize atmospheric conditions and prevent excessive reactive processes, while oxygen is essential for respiration in many organisms.

The other options do not accurately represent the composition of air. For instance, having a composition of 50% oxygen and 50% nitrogen would not be sustainable for life, as such an imbalance would create hazardous conditions due to high levels of oxygen that could lead to toxicity. The notion of 100% oxygen is also not representative of natural air composition and could lead to risk of fire hazards and oxygen toxicity in various environments. Understanding the actual makeup of atmospheric air is fundamental in fields such as hyperbaric medicine, where pressure and gas mixtures play crucial roles in treatment protocols.