Officer Aptitude Rating (OAR) Test 2025 – 400 Free Practice Questions to Pass the Exam

Question: 1 / 400

What percentage of air is composed of nitrogen?

21%

78%

The correct answer highlights that approximately 78% of the Earth's atmosphere is composed of nitrogen. This significant proportion makes nitrogen the primary gas in the atmosphere, with oxygen being the second most abundant at around 21%. Nitrogen plays a crucial role in various biological and chemical processes, including the nitrogen cycle, which is vital for plant growth and ecosystem sustainability.

Understanding this composition is essential for various applications, including environmental science, aviation, and meteorology, as the presence of nitrogen influences weather patterns and the general behavior of the atmosphere. The other options reflect the composition of different gases: 21% refers to oxygen, 1% represents argon, and 0.04% corresponds to carbon dioxide, which are all present in much smaller quantities compared to nitrogen.

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1%

0.04%

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