Basic Firefighter Written Practice Exam

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Prepare for the Basic Firefighter Written Exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

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What percentage of normal air is composed of oxygen?

The correct answer is: 21%

Normal air is composed of approximately 21% oxygen, which is essential for supporting combustion and is crucial for the respiratory needs of most living organisms. This percentage allows for sufficient oxygen for fire to exist and thrive while also being safe for humans and other aerobic life forms to breathe. Understanding the composition of air is vital for firefighters when they analyze fire behavior and dynamics. The right concentration of oxygen not only influences how a fire burns but also impacts the tactics used to control and extinguish flames. The notion that air contains about 21% oxygen is a fundamental fact in fire science and is widely accepted in various safety and health disciplines. Recognizing this composition helps firefighters make informed decisions about ventilation and fire suppression strategies.