Basic Concepts & Zeroth Law of Thermodynamics mcq SET 3

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basic-fitting-mcq
Friends, under this Mechanical section, you will practice Chapter Wise MCQs of ThermodynamicsUnder this, we will practice multiple choice questions and answers of Basic Concepts & Zeroth Law of Thermodynamics.

01. Air is compressed in a cylinder such that the volume changes from 0.2 to 0.02 m3 . The initial pressure is 200 kPa. If the pressure is constant, the approximate work is





ns. (a) : Work done, If the pressure is constant, w = 2 1∫ PdV = P(V2 – V1) = 200 × (0.02 – 0.2) = –36 kJ

02. Match List 1 with List 2 and choose the correct answer from the code List-I (laws of thermodynamics) List-II (Defines) A. First (i) Absolute zero temperature B. Second (ii) Internal Energy C. Zeroth (iii) Temperature D. Third (iv) Entropy





Ans : (4) (A) First→(ii) Internal Energy (B) Second→(iv) Entropy (C) Zeroth→ (iii) Temperature (D) Third → (i) Absolute zero Temperature

03.26. Which of the following processes is irreversible process





Ans. (c) : Throttling process in which No change in enthalpy from state one to state two (h1 = h2) No work is done (W = 0) Process called isenthalpic Process is adiabatic (Q = 0)

04. 27. A cylinder contains 5m3 of ideal gas at a pressure of 1 bar. This gas is compressed in a reversible isothermal process till its pressure increases to 5 bar.





Ans. (a) : Volume (v1) = 5.0m3

05.Which of the following processes are thermodynamically reversible?





Ans. (d) : Throttling, Free expansion, Constant volume and constant pressure processes and adiabatic process are thermodynamically irreversible whereas isothermal and adiabatic processes are thermodynamically reversible.

06. The most efficient method of compressing air is to compress it





Ans. (c) : The work of compression or the steady flow work input to the gas.

07.The internal energy of an ideal gas is function of





Ans. (b) : The internal energy of an ideal gas is function of absolute temperature only. U = f (T only)

08. Work output from a system is at the expense of internal energy is a non flow process carried out





Ans. (c) : Work output from a system is at the expense of internal energy is a non flow process carried out adiabatically.

09.The absolute zero pressure will be





Ans. (a) : Generally, absolute zero pressure is the point where there exist a minimum temperature i.e. zero. That can be possible only when molecular momentum of system become zero. There should not be any motion of particles so there is no collision of particles, kinetic energy nullifies and the temperature becomes zero.

10. An ideal gas can be taken from point K to point N in three different paths: K→L→N, K→N, K→M→N. Which of the following is a true statement?





Ans. (c) : From this diagram we get that the same change in internal energy during each process because of internal energy. It is the property of the system (i.e point function) whereas work and heat for each process will be different because of area under P–V and T–S diagram will be different for each process (i.e path function).

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