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MCQ
861. The entropy in an irreversible cyclic process is -
Remains constant
Decrease
Increase
None of them
862. If the value of n = 0 in the equation PV^n = C, then the process is called-
Constant volume process
Adiabatic process
Constant pressure process
Isothermal process
Constant Pressure Process (n= 0) Isothermal Process (n = 1) [BREB-2014] Adiabatic Process (n = y) Polytropic Process (y> n > 1) Constant Volume Process (n = ∞) PV°=C ⇒ P=C [V°=1]
863. A path 1-2-3 is given. A system absorbs 100 kj as heat and does 60kj of work while along the path 1-4-3, it does 20kj of work. The heat absorbed during the cycle 1-4-3 is-
-140kj
-80kj
-40kj
+60kj
For 1-2-3 cycle. 𝘘1-2-3 = 100 kj W1-2-3 = 60 kj We know, Heat = Internal energy + Work 𝘘1-2-3 = 𝘘1-2-3 + W1-2-3 𝘘1-2-3 = 𝘘1-2-3 - W1-2-3 𝘘1-2-3 = (100-60) kj = 40 kj Again, For 1-4-3 cycle, W1-4-3 = 20kj 𝘘1-2-3 = 𝘘1-4-3 =40kj Again, we know, 𝘘1-4-3 = 𝘘1-4-3 + W1-4-3 = 40 kj+20 kj = 60 kj For 1-2-3 cycle. 𝘘1-2-3 = 100 kj W1-2-3 = 60 kj We know, Heat = Internal energy + Work 𝘘1-2-3 = 𝘘1-2-3 + W1-2-3 𝘘1-2-3 = 𝘘1-2-3 - W1-2-3 𝘘1-2-3 = (100-60) kj = 40 kj Again, For 1-4-3 cycle, W1-4-3 = 20kj 𝘘1-2-3 = 𝘘1-4-3 =40kj Again, we know, 𝘘1-4-3 = 𝘘1-4-3 + W1-4-3 = 40 kj+20 kj = 60 kj
864. The ratio of specific heat at constant pressure (Cp) and specific heat at constant volume (Cv) is-
Equal to one
Less than one
Greater than one
None
865. A mixture of gas expands from 0.03m to 0.06^3m at a constant pressure of 1 mpa and absorbs 84kj of heat during the process. The change in internal energy of the mixture is-
30 kj
54 kj
84 kj
114 kj
866. The entropy in an irreversible cyclic process.
Remain constant
Decreases
Increase
First increase then decrease
867. Which is true for adiabatic process?
∆W = 0
∆Q = 0
∆W=0
∆P=0
868. Efficiency of a Carnot engine is given as 80%. If the cycle direction he reversed, what will be the value of COP of reversed Carnut cycle?
125
0.5
0.25
0.8
869. In vapour compresion refrigeration system, refrigerant occurs as liquid between-.
condeuser and expäision valve
compressor and evaporator
expansion valve and evaporator
compressor and condenser
870. Workdone in free expansion process is-
Zero
Minimum
Maximum
Positive
There is no restraining/opposing force or pressure as expansion occurs against vacuum. So, dw = 0 (in case of free expansion).
871. Change in entropy in a irreversible process-
Ds>d𝘘
ds< d𝘘/T
Ds= d𝘘/T
De ɑ d𝘘 /T
872. For the same heat input and same compression ration.
Otto cycle and diesel cycle are equally efficient
Otto cycle is less efficient than diesel cycle
Efficiency depends mainly on working substance
None of the above
873. Which of the following is an extensive property?
Volume
Pressure
Viscosity
All of the above
874. A process in which the temperature of the working substance remains constant during its expansion or compression is called-
Isothermal process
Hyperbolic process
Adiabatic process
Polytrophic process
875. The extensive properties of a system,-
Are independent of the mass of the system
Depend upon temperature of the system
Depend upon the mass of the system
None of the above
876. Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system-
strong solution is weak solution
weak solution to strong solution
atozng solution to ammonia vapour
ammonia vapour to weak solution
877. In an isolated system, can be transferred between the system and its surrounding.
Only energy
Only mass
Both energy and mass
Neither energy nor mass
878. An ideal gas as compared to a real gas at very high pressure occupies-
More volume
Less volume
Same volume
Unpredictable behaviour
879. In a throttling process-
In a throttling process-
Temperature remains constant
Enthalpy remains constant
Volume remains constant
880. An isobaric process, has constant-
Density
Temperature
Pressure
Volume