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Date: 9-1-2018
1148
Date: 24-10-2018
988
Date: 2-1-2018
1152
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Dihydrogen
Occurrence
Hydrogen is the most abundant element in the universe, and, after oxygen and silicon, is the third most abundant element on Earth, where it occurs mainly in the form of water or combined with carbon in organic molecules (hydrocarbons, plant and animal material). In the Earth’s atmosphere, H2 occurs to an extent of less than 1 ppm by volume, but those of Jupiter, Neptune, Saturn and Uranus contain large amounts of H2
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"عادة ليلية" قد تكون المفتاح للوقاية من الخرف
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ممتص الصدمات: طريقة عمله وأهميته وأبرز علامات تلفه
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أولياء أمور الطلبة يشيدون بمبادرة العتبة العباسية بتكريم الأوائل في المراحل المنتهية
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