MCQ Detailed View

Absolute zero is a fundamental concept in thermodynamics and physical chemistry, representing the lowest limit of the thermodynamic temperature scale. It is defined as the temperature at which the kinetic energy of particles theoretically becomes zero and molecular motion comes to a halt.

The value of absolute zero is approximately:

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  0 Kelvin (0 K)

  
  


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  -273.16°C (commonly approximated as -273.15°C)

  
  


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  -459.67°F

  
  

At absolute zero, entropy reaches its minimum value, as stated by the Third Law of Thermodynamics. Although absolute zero cannot be reached practically, scientists have been able to achieve temperatures extremely close to it using advanced cooling methods like laser cooling and magnetic evaporation techniques.

Why is Absolute Zero Important?

1. 
   

   Temperature Scales:

   
   
   
   
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     The Kelvin scale is based on absolute zero, making it the most scientifically accurate temperature scale for thermodynamic calculations.

     
     
   
   
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     Unlike Celsius or Fahrenheit, the Kelvin scale does not use negative values, simplifying gas law equations.

     
     
   
   
   
   


2. 
   

   Gas Laws:

   
   
   
   
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     According to Charles’s Law, as the temperature of a gas approaches absolute zero, its volume approaches zero.

     
     
   
   
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     This theoretical point helped establish the Kelvin scale.

     
     
   
   
   
   


3. 
   

   Quantum Behavior:

   
   
   
   
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     At ultra-low temperatures near absolute zero, matter exhibits quantum phenomena such as Bose-Einstein Condensates (BECs), where atoms occupy the same quantum state and behave as a single entity.

     
     
   
   
   
   


4. 
   

   Practical Applications:

   
   
   
   
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     Cryogenics, superconductors, and superfluids are studied at temperatures near absolute zero.

     
     
   
   
   • 
     

     These phenomena have applications in MRI machines, quantum computing, and particle physics.

     
     
   
   
   
   

Key Facts

• 
  

  Absolute Zero = 0 K = -273.16°C = -459.67°F

  
  


• 
  

  Represents minimum entropy and energy.

  
  


• 
  

  Not practically achievable but approachable.

  
  


• 
  

  Foundation of the Kelvin scale.

  
  


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  Essential for gas laws and quantum mechanics.

  
  

Thus, the correct answer is -273.16°C (option 4), which represents the concept of absolute zero.