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Date: 5-12-2018
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Date: 12-3-2017
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Date: 11-10-2018
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Calcium is the 20th element in the periodic table. It is a group 2 metal, also known as an alkaline-earth metal, and no populated d-orbital electrons. Calcium is the fifth most abundant element by mass (3.4%) in both the Earth's crust and in seawater. All living organisms require calcium for survival. Calcium is a silver-gray metal which takes its name from the Latin word calx, which means lime. It is the fifth most abundant element in the earth's crust and is widely distributed as limestone (CaCO3), quicklime (CaO) and calcium fluoride.
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تفوقت في الاختبار على الجميع.. فاكهة "خارقة" في عالم التغذية
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أمين عام أوبك: النفط الخام والغاز الطبيعي "هبة من الله"
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قسم شؤون المعارف ينظم دورة عن آليات عمل الفهارس الفنية للموسوعات والكتب لملاكاته
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