Basic Firefighter Written Practice Exam

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Prepare for your firefighter exam with our comprehensive written practice quiz. Test your knowledge and skills through engaging multiple-choice questions designed to reflect the actual exam format. Build confidence and enhance your test-taking skills as you approach your exam day!

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What percentage of normal air is comprised of oxygen?

  1. 10%

  2. 21%

  3. 30%

  4. 50%

The correct answer is: 21%

Normal air is comprised of approximately 21% oxygen by volume. This percentage is a critical aspect of understanding combustion and respiration, as it highlights the availability of oxygen for supporting fire and life. Oxygen is a vital component that fuels combustion; without sufficient oxygen, fires cannot sustain themselves. In the context of firefighting, recognizing that air consists mainly of nitrogen (about 78%) with only a small fraction being oxygen helps firefighters understand the conditions needed for fire to ignite and continue burning. This knowledge is essential when preparing for fire response scenarios, ensuring that firefighters effectively manage ventilation and air supply to control fire behavior and safety.

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