Which of the following elements has an atomic number of 8?

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RRB JE CE 22 Apr 2025 Shift 1 CBT 2 Official Paper
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  1. Hydrogen
  2. Nitrogen
  3. Carbon
  4. Oxygen

Answer (Detailed Solution Below)

Option 4 : Oxygen
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The correct answer is Oxygen.

Key Points

  • Oxygen is a chemical element with the atomic number 8.
  • It is represented by the symbol O in the periodic table of elements.
  • Oxygen is a highly reactive non-metal and an oxidizing agent that readily forms oxides with most elements and compounds.
  • It is essential for most life forms on Earth, as it is a critical component of cellular respiration.
  • Oxygen constitutes about 21% of the Earth's atmosphere by volume.
  • It is also a part of water (H2O) and is necessary for combustion processes.
  • Oxygen was discovered independently by Carl Wilhelm Scheele and Joseph Priestley in the 1770s.

 Additional Information

  •  Hydrogen
    • Hydrogen is the lightest and most abundant element in the universe, with the atomic number 1.
    • It is represented by the symbol H.
    • Hydrogen is primarily found in water (H2O) and is essential for the formation of many compounds.
  • Nitrogen
    • Nitrogen is a chemical element with the atomic number 7.
    • It is represented by the symbol N.
    • Nitrogen makes up about 78% of the Earth's atmosphere and is a crucial component of the biosphere and ecosystems.
  • Carbon
    • Carbon is a chemical element with the atomic number 6.
    • It is represented by the symbol C.
    • Carbon is the basis of all known life on Earth, forming the backbone of organic chemistry.
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