Starter quiz

  • Earth's atmosphere comprises approximately 21% of which gas?
    • 'oxygen' ✓
  • What is the percentage of carbon dioxide in Earth's atmosphere?
    • 78%
    • 21%
    • 1%
    • 0.04%  ✓
  • How old is Earth thought to be?
    • 4 million years
    • 4.5 billion years  ✓
    • 2 million years
    • 200 billion years
  • The atmosphere on Earth has been in roughly the same proportions for how many million years?
    • '200' ✓
  • What name is given to the layer of gas that surrounds a planet?
    • 'atmosphere' ✓
  • What is the name of this process?
    What is the name of this process?
    • respiration
    • combustion
    • photosynthesis  ✓
    • sedimentation
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