UPSC NDA I 2024 General Ability Paper

Concept:Milk of Magnesia is a common name for the suspension of a specific magnesium compound used as an antacid and laxative.Explanation:The chemical formula for Milk of Magnesia is $\mathrm{Mg(OH)_2}$, which is magnesium hydroxide.It is a white, insoluble powder that forms a suspension in water, giving it a milky appearance.In the stomach, it neutralizes hydrochloric acid ($\mathrm{HCl}$) to form magnesium chloride ($\mathrm{MgCl_2}$) and water ($\mathrm{H_2O}$).This neutralisation relieves indigestion and heartburn.The other options do not match the common name:• Magnesium bicarbonate ($\mathrm{Mg(HCO_3)_2}$) is usually found in mineral water, not as a solid suspension.• Magnesium carbonate ($\mathrm{MgCO_3}$) is used as an antacid and in gymnastics for grip, but it is not called Milk of Magnesia.• Magnesium sulphate ($\mathrm{MgSO_4}$), known as Epsom salt, is used in baths and as a laxative, but its common name is not Milk of Magnesia.Thus, the substance known as Milk of Magnesia is exclusively magnesium hydroxide.Answer:Magnesium hydroxide ($\mathrm{Mg(OH)_2}$)