CBSE BoardEnglish MediumSTD 6ScienceAir Around Us1 Mark
Question
How does oxygen occur in nature?
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Answer
Oxygen is found in free state in air as diatomic molecule ($O_{2}$) to the extent of $21\%$ by volume or $23\%$ by weight. In the combined state, it is present in water $(89\%$ by weight$)$, earth’s crust $($about $50\%)$ and in plants and animal tissues $(50-70\%).$
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