Final answer:
Clean, dry air is predominantly composed of nitrogen, oxygen, argon, and carbon dioxide, with nitrogen being the most abundant gas, supporting life and preventing rapid combustion.
Step-by-step explanation:
The dominant gases in a mixture of clean, dry air are primarily nitrogen (N₂; 78.6 percent), oxygen (O₂; 20.9 percent), and in smaller amounts, argon (Ar; around 0.9 percent), with trace amounts of carbon dioxide (CO₂; 0.04 percent). These gases make up most of the volume of the Earth's atmosphere and play crucial roles in both supporting life and affecting global processes such as combustion and temperature regulation. While nitrogen is the most abundant, preventing rapid burning, oxygen is crucial for aerobic respiration and life's molecular processes, and argon acts as an inert gas. Carbon dioxide, while present in small amounts, is significant for its role in the greenhouse effect and plant photosynthesis.
Minor gases in the atmosphere, aside from water vapor, include neon and helium, which are present since the Earth's formation, as well as variable gases like ozone and carbon monoxide, which have varying abundances due to anthropogenic sources and natural processes.