MCQ Detailed View

Caustic potash is the common name for potassium hydroxide (KOH), a strong inorganic base. It is an alkali metal hydroxide similar to sodium hydroxide (NaOH), which is called caustic soda. Both are highly caustic and corrosive, but KOH is specifically referred to as caustic potash because potassium compounds were historically obtained from “pot ashes.”

Potassium hydroxide is a white, deliquescent solid that readily absorbs moisture and carbon dioxide from the air. It is extremely soluble in water and forms a strongly alkaline solution. When dissolved in water, KOH dissociates completely into potassium ions (K⁺) and hydroxide ions (OH⁻). The hydroxide ions make the solution strongly basic, capable of neutralizing acids and reacting vigorously with many substances.

KOH is widely used in industry and laboratories. It is employed in the manufacture of soft soaps, liquid soaps, and detergents. Unlike sodium soaps, which are hard and solid, potassium soaps are softer and more soluble in water. KOH is also used in the preparation of fertilizers, biodiesel production, alkaline batteries, and as a strong base in various chemical syntheses.

Comparing the given options:

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  NaOH is sodium hydroxide, also known as caustic soda, not caustic potash.

  
  


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  KOH is potassium hydroxide, and this is the compound called caustic potash.

  
  


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  NaCl is sodium chloride, commonly known as table salt, and is not an alkali.

  
  


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  NaBH₄ is sodium borohydride, a reducing agent, but not referred to as caustic potash.

  
  

Thus, the correct answer is KOH, because potassium hydroxide is universally known as caustic potash in inorganic chemistry.