Basic Concepts & Zeroth Law of Thermodynamics 1

These are the Questions which were asked in previous exams of Sate PSC like BPSC, UPPSC, TNPSC, JPSC and many more exams. All these Questions are answered with proper solution.

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1.The energy of the isolated system is always a constant, which is given by:

(a) Zeroth law of thermodynamics

(b) First law of thermodynamics

(d) Third law of thermodynamic

(e) Law of stable equilibrium

(b):Isolated System–An isolated system is a thermodynamic system that cannot exchange either energy or mass outside the boundaries of the system.

So, ∆E = 0, ∆m = 0

So from the first law of thermodynamics energy of the

isolated system will be remain constant.

Answer

2. A series of operations, which takes place in a certain order and restore the initial conditions at the end,is known as

(a) Reversible cycle

(b) Irreversible cycle

(d) None of these

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UPPSC AE 12.04.2016 Paper-II

Ans. (c) : Thermodynamic cycle– A series of operation which takes place in a certain order and restore the initial conditions at the end, is known as thermodynamic cycle.

Answer

3. Heat and work are :

(a) Intensive properties

(b) Extensive properties

(d) Path functions

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Ans. (d) : Heat and work are path function similarities between heat and work :

(i) Both are recognized at the boundary of the system, as they cross the boundary phenomena.

(ii) System possesses - energy, but neither heat and work.

(iii) Both are associated with process not state. Heat and work have no meaning at a state.

(iv) Both are path functions.

• Path function- Magnitude depends on the path followed during the process as well as the end states.

• Point function- Magnitude depends on state only and not a how the system approaches that state.

Answer

4. What are the properties of a thermodynamic system whose value for the entire system is equal to the sum of their values for individual parts of the system?

(a) Thermodynamic properties

(b) Extensive properties

(d) Specific properties

TNPSC AE 2018

Ans. (b) : Extensive properties- Extensive properties of matter that changes as the amount of matter changes

Example- Volume, enthalpy, entropy etc.

Intensive properties- An intensive properties is a bulk property, meaning that it is a local physical property of a system that does not depends on the system size or the amount of material in the system.

Example- Pressure, temperature, refractive index, density and hardness of object.

Answer

5. Consider the following properties:

1. Temperature

2. Viscosity

3. Specific entropy

4. Thermal conductivity

Which of the above properties of a system is/are intensive?

(a) 1 only

(b) 2 and 3 only

(d) 1, 2, 3 and 4

Gujarat PSC AE 2019

Ans : (d) : Intensive properties of system are as follows-

• Temperature

• Viscosity

• Specific entropy

• Thermal conductivity

• Specific volume

• Specific enthalpy

Answer

6. An open system

(a) is a specified region where transfers of energy and / or mass take place

(b) is a region of constant mass and only energy is allowed to cross the boundaries

(d) has an enthalpy transfer across its boundariesand the mass within the system is not necessarily constant

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Ans : (a)

Answer

7. Match the following :

1.Closed system

2.Open system

3.Pump

4.Turbine

5.Nozzle

a. Increase in static pressure

b. Increase in kinetic energy

c. Heat, mass and work interact

d. Heat and work interact

e. Delivers work

(a) 1–d, 2–c, 3–a, 4–e, 5–b

(b) 1–c, 2–d, 3–b, 4–e, 5–a

(d) 1–d, 2–c, 3–e, 4–a, 5–b

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Ans. (a) :

1. Closed system-Heat and work interact

2. Open system-Heat, mass and work interact

3. Pump-Increase in static pressure

4. Turbine-Delivers work

5. Nozzle-Increase in kinetic energy

Answer

8. The law which provides the basis of temperature measurement is:

(a) Third law of thermodynamics

(b) Zeroth law of thermodynamics

(d) Second law of thermodynamics

TNPSC 2019

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Ans. (b): 1. Zeroth law of thermodynamics provides the basis of temperature measurement.

2. First law of thermodynamics provides conservation law of energy.

3. Second law of thermodynamics provides the basic concept of entropy.

Answer

9. Which one of the following is the extensive property of the system?

(a) Volume

(b) Pressure

(d) Density

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Ans:(a):These properties are dependent on mass e.g. volume, energy, Heat capacity (Cv, Cp), enthalpy, entropy.

Answer

10. Pressure exerted by a gas in a closed container is:

(a) Weak function of Density and Temperature

(b) Weak function of Density and Volume

(d) Strong function of Density and Volume

OPSC AEE 2019 PAPER - II

Ans :(c):Pressure exerted by a gas in a closed container is strong function of density and temperature.

Answer

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11. Which of the following items is not a path function?

(a) Heat

(b) Work

(d) Thermal conductivity

BPSC AE 2012 Paper - V

Ans : (d) : Thermal conductivity is not a path functions.

Answer

12. Which one of the properties given below is an intensive property of the system

(a) composition

(b) volume

(d) entropy

TSPSC AEE 2015

Ans. (a) : Volume, Kinetic energy and entropy are the example of extensive property where as composition is the example of intensive property.

Answer

13. Which pair of the following alternatives is correctly matched ?

List – I List – II

(a) Heat – Point function

(b) Energy – Path function

(d) Gibbs function – Path function

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Ans. (c) : Entropy – Second law of thermodynamics

Answer

14. Thermodynamic work is the product of

(a) Two intensive

(b) Two extensive properties

(d) An extensive property and change in an intensive property

UPPSC AE 12.04.2016 Paper-II

Ans:(c)For quasistatic process work done is calculated by ∫ P.dV

Pressure = Intensive property.

Volume (dV) = change in an extensive property.

Thermodynamic work is the product of An intensive property and change in an extensive property.

Answer

15. Bi-Metallic strips made of two different materials bend during a rise is temperature because of

(a) Differences in coefficient of linear expansion

(b) Differences in elastic properties

(d) Difference in stress

TNPSC AE 2014

Ans.(a):Bi-Metallic strips made of two different materials bend during a rise is temperature because of differences in coefficient of linear expansion.

Answer

16. The gauge pressure in a truck tire before and after the journey was recorded as 200 kPa and 220 kPa respectively at the location where atmospheric pressure and temperature was 100 kPa and 27ºC respectively.How much the rise in temperature of tire air after trip?

(a)20ºC

(b)27ºC

(d)Insufficient data

OPSC AEE 2019 PAPER - II

Ans : (c)

Answer

17. The condition for the reversibility of a cycle is

(a) the pressure and temperature of the working substance must not differ, appreciably, from those of the surroundings at any stage in the process

(b) all the processes, taking place in the cycle of operation, must be extremely slow

(d) all of the above

Gujarat PSC AE 2019

Ans:(d) : The condition for the reversibility of a cycle is the pressure and temperature of the working substance must not differ, appreciably from those in the process.The working parts of the engine must be friction free.

Answer

18. Which of the following is an example of irreversible process?

(a) Polytropic expansion of fluid

(b) Unrestricted expansion of gases

(d) Electrolysis

JPSC AE 2013 Ist Paper

Ans.(b):

Irreversible process- In an irreversible process, there is a loss of heat due to friction, radiation and conduction. In an actual practice, most of the processes are irreversible to some degree The main causes for the irreversibility may be.

(i) Mechanical and fluid friction

(ii) Unrestricted expansion

(iii) Heat transfer with a finite temperature difference.

Answer

19. Which of the following is considered as thermodynamic potential?

(a) Temperature

(b) Internal energy

(d) Entropy

JPSC AE 2013 Ist Paper

Ans.(c):Enthalpy is considered as thermodynamic property.

Answer

20. Ratio of absolute temperature at two different states in an adiabatic process is:

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UKPSCAE-2013, Paper-II

Answer

MECHANICAL ENGINEERING BOOKS PDF Free Download for GATE and UPSC ESE

For the aspirants of UPSC ESE and GATE these books are very important (or must read book). For reading concepts of Thermodynamics you can read Thermodynamics An Engineering Approach by Cengel and Boles. After reading this book you will get a crystal clear concept. The Exercise questions given in exercise of this book will make your concepts strong and you can easily solve UPSC ESE Objective Questions. For UPSC Mains solve all the problems of Thermodynamics by P K Nag. This will be sufficient for Thermodynamics. For Power Plant you can refer made easy notes wchich is also provided in this website(Below is the link for the Mechanical Engineering notes). Hand Written Mechanical Engineering Notes by Mohit Chouksey Free Download--- Click Here After reading made easy notes you can prefer Power Plant by P K Nag and solve all the problems in this book. This will be sufficient for ESE and GATE. Alongwith it you have to solve previous year questions. For UPSC ESE try to solve ...

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