Minnesota Boiler License Practice Exam

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Study for the Minnesota Boiler License Exam. Deepen your knowledge with expertly designed flashcards and multiple choice questions, each complete with helpful hints and detailed explanations. Get prepared for your licensing success!

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What is the approximate percentage of oxygen by volume in air?

21%.
14%.
79%.
18%.

The correct answer is: 21%.

The approximate percentage of oxygen by volume in air is around 21%. This value is based on the composition of the Earth's atmosphere, which is primarily made up of nitrogen (about 78%) and oxygen. The remaining percentage consists of other gases, such as argon and carbon dioxide. The 21% figure for oxygen is well-established and is crucial for various applications, including combustion processes and supporting life, as it provides the necessary oxygen for respiration in humans and animals. Understanding the composition of air is essential for anyone involved in boiler operations, where the combustion efficiency and emissions are influenced directly by the available oxygen.