MCQ Detailed View

Magnesium is one of the few elements that can be extracted directly from sea water. Sea water contains many dissolved minerals, including magnesium chloride (MgCl₂). On average, sea water contains about 0.13% magnesium by mass, making it a significant source for commercial extraction.

To obtain magnesium from sea water, the process typically begins with precipitation. Lime (CaO) is added to the sea water, which reacts with the dissolved magnesium chloride to form magnesium hydroxide (Mg(OH)₂). This compound is then filtered, washed, and heated to convert it into magnesium oxide (MgO). Finally, magnesium oxide is subjected to electrolysis to separate pure magnesium metal.

Magnesium is a lightweight metal that is highly valued in industrial applications. It is used in the production of aircraft parts, automobile components, firecrackers, and alloys like magnesium-aluminum. It is also biologically essential and plays a role in human health, especially in muscle and nerve function.

Let’s look at the incorrect options:

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  Beryllium is a rare metal primarily extracted from the mineral beryl. It is not found in significant quantities in sea water and is not economically extracted from it.

  
  


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  Aluminium is the most abundant metal in the Earth's crust and is obtained from bauxite ore, not sea water.

  
  


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  “None of these” is incorrect because magnesium is indeed extracted from sea water.

  
  

Therefore, magnesium is the correct answer. This topic falls under Chemistry as it deals with element separation, electrolysis, and the chemical composition of natural sources like sea water.