MCQ Detailed View

Refrigeration is one of the most important technological advancements in modern life, and its development is strongly linked with the use of specific refrigerant gases. Since the invention of refrigerators, three major gases have been considered significant in their widespread use:

1. 
   

   Ammonia (NH₃):
   Ammonia was among the first refrigerants used in the late 19th and early 20th centuries. It is highly efficient in absorbing heat and is still widely used in industrial refrigeration. However, because it is toxic and corrosive, it was not ideal for domestic refrigerators.

   
   


2. 
   

   Freon (CFCs – Chlorofluorocarbons such as R-12):
   Introduced in the 1930s, Freon quickly became the most common refrigerant in household refrigerators. It was considered safe for consumers because it was stable, odorless, and non-toxic. However, by the 1970s and 1980s, scientists discovered that CFCs cause severe ozone layer depletion, which led to environmental concerns and international bans under the Montreal Protocol (1987).

   
   


3. 
   

   Hydrofluorocarbons (HFCs – e.g., R-134a):
   As a replacement for CFCs, HFCs were introduced. They are ozone-friendly (do not damage the ozone layer), but they still contribute to global warming. Despite that, HFCs became the standard refrigerant for decades and are still widely used, though new eco-friendly gases such as hydrocarbons (R-600a, isobutane) are increasingly replacing them.

   
   

✅ Key Facts to Remember

• 
  

  Three major refrigerant gases: Ammonia, Freon (CFCs), and HFCs.

  
  


• 
  

  Ammonia → first used, still in industry.

  
  


• 
  

  Freon (CFCs) → safe for homes but banned due to ozone depletion.

  
  


• 
  

  HFCs → safer for ozone but contribute to global warming.

  
  


• 
  

  New trend → Hydrocarbons (like isobutane) for eco-friendly refrigeration.

  
  

👉 Therefore, the correct answer is 3 (Option B).