The Earth's atmosphere weighs about 5.5 quadrillion tons.
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The gas that gives rotten eggs their distinctive foul smell may slow ageing and block damaging chemical reactions inside cells, according to scientists in China.
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Balsa wood is classified as a hard wood!
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Sound at the right vibration can bore holes through a solid object.
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In Arizona, a solar wind energy tower has been proposed that would generate as much energy as the Hoover Dam.
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Iron weighs more after it rusts.
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Airports that are at higher altitudes require a longer airstrip due to lower air density.
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