Q.11

For a spontaneous process, the total entropy change
(ΔS_system + ΔS_surroundings) is:

1. equal to zero
2. greater than zero
3. less than zero for endothermic process
4. less than zero for exothermic process
   

   Correct Answer: (B) Greater than zero

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   Concept Behind the Question

   This question is based on the Second Law of Thermodynamics, which states:

   For any spontaneous (natural) process, the entropy of the universe always increases.

   Mathematically:

   ΔStotal=ΔSsystem+ΔSsurroundings​

   For spontaneity:

   ΔStotal>0

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   Step-by-Step Explanation

    What is Entropy (S)?

   Entropy measures:

   • disorder

   • randomness

   • energy dispersal

   Higher entropy → more randomness → more stability → spontaneous direction.

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   Explanation of Each Option

    (A) Equal to zero

   If:

   ΔStotal=0

   Then the process is reversible, not spontaneous.

   👉 Reversible processes are ideal and theoretical, not natural.

   So, incorrect.

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    (B) Greater than zero

   If:

   ΔStotal>0

   Entropy of the universe increases.

   👉 This is the condition for spontaneous processes.

   Examples:

   • melting of ice above 0°C

   • gas expansion

   • diffusion

   • rusting

   So, correct answer.

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    (C) Less than zero for endothermic

   Endothermic process means:

   ΔH>0

   But spontaneity depends on both enthalpy and entropy, not only heat absorbed.

   Some endothermic reactions are spontaneous if:

   TΔS>ΔHT

   Example: melting of ice

   Thus, entropy total is not negative.

   So, incorrect.

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    (D) Less than zero for exothermic

   Exothermic means:

   ΔH<0

   But even exothermic processes can be non-spontaneous if entropy decreases too much.

   Spontaneity still requires:

   ΔStotal>0

   So, incorrect.

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   Quick Rule to Remember

   Process Type	ΔSₜₒₜₐₗ	Nature
   Spontaneous	> 0	Natural
   Reversible	= 0	Ideal
   Non-spontaneous	< 0	Impossible naturally

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   Final Conclusion

   For every spontaneous process:

   ΔSsystem+ΔSsurroundings>0​

   Therefore,

   Answer = (B) Greater than zero

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    SEO Introduction

   Understanding the total entropy change for spontaneous process is essential in thermodynamics and chemistry. According to the second law of thermodynamics, spontaneous reactions occur only when the entropy of the universe increases. This article explains the concept with formulas, option-wise solutions, and easy examples for quick learning.