geography MCQ #491

The percentage of oxygen in the atmospheric air is approximately?

geography MCQ #491

  1. Question 1

    Q1. The percentage of oxygen in the atmospheric air is approximately?

    • A) 10 per cent
    • B) 21 per cent
    • C) 30 per cent
    • D) 40 per cent

    Answer: 21 per cent

    Explanation: Oxygen constitutes approximately 21% of Earth's atmosphere by volume (20.9%), while nitrogen makes up about 78%, with argon and other gases comprising the remainder.