Question 5: Choose the correct answer to the following question: about what percentage of the volume is oxygen in the air?

Question 5: Choose the correct answer to the following question: about what percentage of the volume is oxygen in the air? A. 15% B. 78% C. 79% D. 21% EASY answer Composition of air: 21% oxygen, 78% nitrogen and 1% other gases. ===============

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