-min%20(5).webp "basic-fitting-mcq")
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).