What is the percentage of oxygen in a...

Question 1 of 270705eccef9ebacbc34ba4d46614

What is the percentage of oxygen in a typical sample of uncontaminated air?

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Question 1 of 27070

Q

What is the percentage of oxygen in a typical sample of uncontaminated air?

🔍 Key Concepts

• Normal composition of dry atmospheric air at sea level • Typical oxygen percentage needed to support human life and combustion • Difference between oxygen concentration and total air pressure

💭 Think About

• Think about what you learned in basic first aid or firefighting: what oxygen percentage is considered normal breathable air? • Which of these percentages would be too low to safely support normal human activity without causing hypoxia (oxygen deficiency)? • Firefighting training often mentions a minimum oxygen level below which flames will not sustain well. How does that compare with normal air?

✅ Before You Answer

• Eliminate any options that are clearly too low to support normal breathing and open flame combustion • Recall that nitrogen makes up most of the air; oxygen is the next largest component — think about their approximate percentages • Make sure you are thinking of percentage by volume of dry air at sea level, not oxygen in medical equipment or compressed gas cylinders