What percentage of oxygen is found in the atmosphere?

The correct percentage of oxygen in the Earth's atmosphere is approximately 21%. This value is significant because it defines the composition of the air we breathe, which is essential for life. Oxygen is crucial for cellular respiration in animals and plants, and a consistent presence in this proportion enables biological processes to function effectively.

Understanding the composition of the atmosphere is vital not only for biology but also in various practical applications within power engineering and environmental sciences. For example, combustion efficiency in engines and boilers is directly related to the availability of oxygen; thus, knowing that 21% of the atmosphere consists of oxygen helps engineers design systems that operate efficiently and safely in a real-world context.

By recognizing this standard atmospheric composition, students and professionals in power engineering can better understand the implications for combustion processes and air quality management.