OCTCO/OCTF Exit Exam • Set 7 Question 6 of 30

What % of air is made up by oxygen?

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Direct Answer

Option B: 21%

Standard atmospheric ambient air is composed of approximately 20.9% (approx. 21%) oxygen, 78% nitrogen, and 1% argon and other trace gases.

All Options

78%

21% (Correct Answer)

100%

Detailed Explanation & Context

Standard atmospheric ambient air is composed of approximately 20.9% (approx. 21%) oxygen, 78% nitrogen, and 1% argon and other trace gases.

Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • Oil and Chemical Tanker Cargo Operations (OCTCO/OCTF).

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