Saturday, July 10, 2021

Second Law of Thermodynamics (Direction of flow of heat) With MCQS Useful For Different University Exams, IIT, NEET, M.Sc. Entrance, PGT



Kelvin Statement-

It is impossible to get a continuous supply of work from a body by colling it to a temperature lower than that of its surrounding.

Planks Statement-

It is impossible to construct an engine which work in a complete cycle will produce no effect other than the raising of a weight and cooling of a reservoir.

Kelvin-Plank Statement-

It is impossible to construct an engine which operating in a cycle has the sole effect of extracting heat from a reservoir and performing an equivalent amount of work.

Clausius Statement-

It is impossible for a self-acting machine working in a cyclic process unaided by external agency to transfer heat from a body at a lower temperature to a body at a higher temperature.

1. Kelvin Planck’s law deals with

(a) conservation of heat                                          

(b) conservation of work

(c) conversion of heat into work                            

(d) conversion fo work into heat

Answer : c

2. According to Clausius statement of second law of thermodynamics

(a) heat can’t be transferred from low temperature source to high temperature source

(b) heat can be transferred for low temperature to high temperature source by using refrigeration cycle.

(c) heat can be transferred from low temperature to high temperature source if COP of process is more than unity

(d) heat can’t be transferred from low temperature to high temperature source without the aid of external energy

(e) all of the above.

Answer : d

3. Which of the following laws was formulated by Nernst?

(a)First law of thermodynamics         

(b) Second law of thermodynamics

(c)Third law of thermodynamics         

(d) None of the above

Answer: (c)

 4. Second law of thermodynamics is defined the

(a) Enthalpy                                                                

(b) Entropy 

(c) Internal energy                                                       

(d) Pressure 

Answer: b

5. Heat transfer take place according to ......

(a) Zeroth law of thermodynamics         

(B) First law of thermodynamics 

(c) Second law of thermodynamics         

(d) Third law of thermodynamics 

Answer: c

6. Which law of thermodynamics says that efficiency of a heat engine cannot be 1?

(a)First                                              

(b) zero

(c) second                                           

(d) third

Answer: c

 Hint- entropy change in an Irreversible process has to be positive this means that heat given to an engine cannot be totally converted into work therefore efficiency cannot be 1

7. The second law of thermodynamics states that

(a)  Entropy of an isolated system and never decrease over time

(b) Entropy of a pure crystalline substance at zero kelvin is zero

(c)  Energy is conserved

(d) Entropy of a system can never decrease

 Answer: a

 

 

2 comments:

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