Which of the following laws states that "When a system is at zero absolute temperature, the entropy of system is zero"?

Concept:

• Third law of thermodynamics: As the temperature approaches absolute zero, the entropy of a system/crystal approaches a constant minimum.

ΔST at 0 K = 0

Where ΔS = change in entropy 

EXPLANATION:​

• The Third Law of Thermodynamics tells us about the entropy of a perfect crystal at absolute zero temperature. So option 1 is correct.
• The relation between heat and work is given by the first law of thermodynamics. 
• There is no perfect relation between the evolution of entropy of a system with the time.
• The conservation of mass is not explained by any law of thermodynamics.

Additional Information

There are 4 laws to thermodynamics:

Zeroth law of thermodynamics: 

• If two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.

The first law of thermodynamics: 

• Energy can neither be created nor destroyed. It can only change forms. In any process, the total energy of the universe remains the same.
• For a thermodynamic cycle, the net heat supplied to the system is equals the net work done by the system.

ΔQ = ΔU + ΔW

where ΔQ = change in heat, ΔU = change in internal energy and ΔW = change in work done

Second Law of Thermodynamics:

1. Clausius statement: It is impossible for a self-acting machine to transfer heat from a colder body to a hotter one without the aid of an external agency
2. Kelvin-Planck’s statement: It is impossible to design an engine that extracts heat and fully utilizes it into work without producing any other effect.

Third law of thermodynamics:

•  As the temperature approaches absolute zero, the entropy of a system/crystal approaches a constant minimum.
• ΔST = 0 K = 0
• Where ΔS = change in entropy