MCQ Detailed View

Sublimation is a separation technique based on the physical property of certain solids to change directly into vapor without passing through the liquid phase. Substances such as naphthalene, camphor, iodine, and ammonium chloride undergo sublimation, while non-sublimable solids like sand, salt, or iron filings remain unchanged under the same conditions.

In the given options:

1. 
   

   Sand and Iron filings:

   
   
   
   
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     Neither sand nor iron filings undergo sublimation.

     
     
   
   
   • 
     

     They must be separated by other physical methods like a magnet (for iron) or filtration.

     
     
   
   
   
   


2. 
   

   Sand and Naphthalene:

   
   
   
   
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     Naphthalene sublimates easily when heated, producing vapors that can later be condensed back into solid crystals.

     
     
   
   
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     Sand, being non-volatile and non-sublimable, remains behind.

     
     
   
   
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     This makes sublimation the ideal method to separate the two.

     
     
   
   
   
   


3. 
   

   Both A & B:

   
   
   
   
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     Incorrect, because sublimation only works for option B, not option A.

     
     
   
   
   
   


4. 
   

   None:

   
   
   
   
   • 
     

     Incorrect, because sand and naphthalene can definitely be separated by sublimation.

     
     
   
   
   
   

This process works on the principle of different volatility. The sublimable substance is collected as purified solid after condensation, while the non-sublimable component remains in the container.

Applications of sublimation separation:

• 
  

  Purification of camphor in pharmaceuticals.

  
  


• 
  

  Separation of iodine crystals in laboratories.

  
  


• 
  

  Removal of naphthalene from mixtures in the dye and textile industries.

  
  

Thus, the correct answer is Sand and Naphthalene, as only this mixture contains a sublimable component.