GK
ELEMENTS COMPOUNDS SUBSTANCES METALS AND NON METALS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Sodium
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Calcium
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Potassium
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Magnesium
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Detailed explanation-1: -The answer is Sodium. Sodium reacts vigorously with oxygen and even with water.
Detailed explanation-2: -Sodium metal reacts vigorously with water.
Detailed explanation-3: -Sodium reacts violently with water because it is much more active than hydrogen. Although water is covalent, not ionic, it is helpful sometimes to consider water to be [H+][OH-], since after all hydrogen has a slight excess of positive charge.
Detailed explanation-4: -Metals such as potassium and sodium react violently with cold water. The reaction is so violent and exothermic that the evolved hydrogen immediately catches fire.
Detailed explanation-5: -Halogen acids, such as hydrochloric acid, react vigorously with sodium, yielding the sodium halides. The reactions are highly exothermic, with heats of reaction (energy given off) of −71.8 and −76.2 kcal, respectively, for the reactions with hydrofluoric and hydrochloric acids.