For a compressible fluid, sonic velocity is

where , R and T are respectively the ratio of specific heats, gas constant and temperature in K

always greater then the velocity of fluid at any location

Consider the following two processes; I. A heat source at 1200 K loses 2500 kJ of heat to a sink at 800 K II. A heat source at 800 K loses 2000 kJ of heat to a sink at 500 K Which of the following statements is true?

Irreversibility associated in both the processes are equal

Process I is more irreversible than Process II

Process II is more irreversible than Process I

Irreversibility associated in both the processes are equal

Both the processes are reversible

Determine the correctness or otherwise Assertion (A) and the Reason (R). Assertion (A): In a power plant working on a Rankine cycle, the regenerative feed water heating improves the efficiency of the steam turbine. Reason (R): The regenerative feed water heating raises the average temperature of heat addition in the Rankine cycle.

Both (A) and (R) are true but (R) is NOT the correct reason for (A)

Both (A) and (R) are true and (R) is the correct reason for (A)

Both (A) and (R) are true but (R) is NOT the correct reason for (A)

Determine the correctness or otherwise of the following Assertion (A) and the Reason (R). Assertion (A):Condenser is an essential equipment in a steam power plant. Reason (R): For the same mass flow rate and the same pressure rise, a water pump requires substantially less power than a steam compressor.

Both (A) and (R) are true and (R) is the correct reason for (A)

Both (A) and (R) are true but (R) is NOT the correct reason for (A)

A system undergoes a State change from 1 to 2.According to the second law of thermodynamics, for the process to be feasible, the entropy change, S2 S1 of the system

can be positive, negative or zero

Water has a critical specific volume of 0.003155 m3/kg. A closed and rigid steel tank of volume 0.025 m3 contains a mixture of water and steam at 0.1 MPa. The mass of the mixture is 10 kg. The tank is now slowly heated. The liquid level inside the tank

may rise or fall depending on the amount of heat transferred

A rigid container of volume 0.5 m3 contains 1.0 kg of water at 120 C (vf = 0.00106 m3/kg, vg = 0.8908 m3/kg). The state of water is

a mixture of saturated liquid and saturated vapor

248 + Mcqs in Thermodynamics Miscellaneous in Thermodynamics Page 1 McqOptions

1.	If the pressure at station Q is 50 kPa, the change in entropy (s_Q s_p) in kJ/kgK is
A.	0.155
B.	0
C.	0.160
D.	0.355
Answer» D. 0.355

Discussion

2.	Steam enters a well insulated turbine and expands isentropically throughout. At an intermediate pressure, 20 percent of the mass is extracted for process heating and the remaining steam expands isentropically to 9 kPa. Inlet to turbine: P = 14 MPa, T = 560 C, h = 3486 kJ/kg, s = 6.6 kJ/(kgK) Intermediate stage: h = 276 kJ/kg Exit of turbine: P = 9 kP_a, h_f = 174 kJ/kg, h_g = 2574 kJ/kg, s_f = 0.6 kJ/(kgK), s_g = 8.1 kJ/(kgK) If the flow rate of steam entering the turbine is 100 kg/s, then the work output (in MW) is____.
A.	125MW
B.	125.56 MW
C.	129.56 MW
D.	525.56 MW
Answer» C. 129.56 MW

Discussion

3.	A gas is heat ed in a duct as it flows over a resistance heater. Consider a 101 kW electric heat ing syst em. The gas ent ers the heat ing section of the duct at 100 kPa and 27 C with a volume flow rate of 15 m /s. If heat is lost from the gas in the duct to the surroundings at a rate of 51 kW, the exit temperature of the gas is (Assume constant pressure, ideal gas, negligible change in kinetic and potential energies and constant specific heat: C_p = 1 kJ/kg. K; R = 0.5 kJ/kg K).
A.	37 C
B.	76 C
C.	53 C
D.	32 C
Answer» E.

Discussion

4.	In order to burn 1 kilogram of CH₄ completely, the minimum number of kilograms of oxygen needed is (take atomic weights of H, C and O as 1, 12 and 16 respectively)
A.	3
B.	4
C.	5
D.	6
Answer» C. 5

Discussion

5.	One kg of air (R = 287 J/kgK) undergoes an irreversible process between equilibrium state 1 (20 C, 0.9 m³) and equilibrium state 2 (20 C, 0.6 m³). The change in entropy s₂ s₁ (in J/ kgK) is ______.
A.	- 116.36 J /kgK
B.	116.36 J /kgK
C.	- 117.36 J /kgK
D.	116.36 J /kgK
Answer» B. 116.36 J /kgK

Discussion

6.	An ideal gas of mass m and temperature T₁ undergoes a reversible isothermal process from an initial pressure P₁ to final pressure P₂. The heat loss during the process is Q. The entropy change S of the gas is
A.	Zero
Answer» C.

Discussion

7.	One kg of an ideal gas (gas constant R = 287 J/ kgK) undergoes an irreversible process from state-1 (1 bar, 300 K) to state-2 (2 bar, 300 K). The change in specific entropy (s₂ s₁) of the gas (in J/kgK) in the process is _______.
A.	- 198.93 J/kg K
B.	198.93 J/kg K
C.	199.93 J/kg K
D.	- 199.93 J/kg K
Answer» B. 198.93 J/kg K

Discussion

8.	An ideal gas undergoes a process from state 1 (T₁ = 300 K, p₁ = 100 kPa) to state 2 (T₂ = 600 K, p₂ = 500 kPa). The specific heats of the ideal gas are: c_p = 1 kJ/kg-K and c_v = 0.7 kJ/kg-K. The change in specific entropy of the ideal gas from state 1 to state 2 (in kJ/kg-K) is _________ (correct to two decimal places)
A.	0.3 kJ/kg-K
B.	0.2 kJ/kg-K
C.	0.4 kJ/kg-K
D.	- 0.3 kJ/kg-K
Answer» B. 0.2 kJ/kg-K

Discussion

9.	One kg of an ideal gas (gas constant, R= 400 J/ kgK; specific heat at constant volume, c_p = 1000 J/kgK) at 1 bar, and 300 K is contained in a sealed rigid cylinder. During an adiabatic process, 100 kJ of work is done on the system by a stirrer. The increase in entropy of the system is _______ J/K.
A.	287.68 J/K
B.	187.68 J/K
C.	387.68 J/K
D.	277.68 J/K
Answer» B. 187.68 J/K

Discussion

10.	A turbocharged four-stroke direct injection diesel engine has a displacement volume of 0.0259 m³ (25.9 liters). The engine has an output of 950 kW at 2200 rpm. The mean effective pressure (in MPa) is closest to
A.	2
B.	1
C.	0.2
D.	0.1
Answer» B. 1

Discussion

11.	In a 3-stage air compressor, the inlet pressure is p1, discharge pressure is p₄ and the intermediate pressures are p₂ and p₃ (p₂ < p₃). The total pressure ratio of the compressor is 10 and the pressure ratios of the stages are equal. If p₁ = 100 kPa, the value of the pressure p₃ (in kPa) is _______.
A.	464.15 kPa
B.	454.15 kPa
C.	474.15 kPa
D.	460.15 kPa
Answer» B. 454.15 kPa

Discussion

12.	An automobile engine operates at a fuel air ratio of 0.05, volumetric efficiency of 90% and indicated thermal efficiency of 30%. Given that the calorific value of the fuel is 45 MJ/kg and the density of air at intake in 1 kg/m³, the indicated mean effective pressure for the engine is
A.	6.075 bar
B.	6.75 bar
C.	67.5 bar
D.	243 bar
Answer» B. 6.75 bar

Discussion

13.	Propane (C₃H₈) is burned in an oxygen atmosphere with 10% deficit oxygen with respect to the stoichiometric requirement. Assuming no hydrocarbons in the products, the volume percentage of CO in the products is___.
A.	14.29%
B.	13.29%
C.	17.29%
D.	15.29%
Answer» B. 13.29%

Discussion

14.	For a compressible fluid, sonic velocity is
A.	a property of the fluid
B.	always given by
C.	where , R and T are respectively the ratio of specific heats, gas constant and temperature in K
D.	always greater then the velocity of fluid at any location
E.	Both A and B
Answer» F.

Discussion

15.	An air breathing air craft is flying at an altitude where the air density is half the value at ground level. With reference to the ground level, the air- fuel ratio at this altitude will be
A.	3
B.
C.	2
D.	4
Answer» D. 4

Discussion

16.	In a spark ignition engine working on the ideal Otto cycle, the compression ratio is 5.5. The work output per cycle (i.e., area of the P V diagram) is equal to 23.625 10⁵ V_cJ, where V_c is the clearance volume in m³. The indicated mean effective pressure is
A.	4.295 bar
B.	5.250 bar
C.	86.870 bar
D.	106.300 bar
Answer» C. 86.870 bar

Discussion

17.	In a steam power plant operating on a ideal Rankine cycle, superheated steam enters the turbine at 3 MPa and 350 C. The condenser pressure is 75 kPa. The thermal efficiency of the cycle is ________%. Given data: For saturated liquid, at p = 75 kPa, hf = 384.39 kJ/kg, v_f = 0.001037 m³/kg, s_f = 1.213 kJ/kgK. At 75 kPa, h_fg = 2278.6 kJ/kg, s_fg = 6.2434 kJ/kgK At P = 3 MPa and T = 350 C (superheated steam), h = 3115.3 kJ/kg, s = 6.7428 kJ/kgK.
A.	0.26 or 26%
B.	0.25 or 25%
C.	0.27 or 27%
D.	0.36 or 36%
Answer» B. 0.25 or 25%

Discussion

18.	Consider the following two processes; I. A heat source at 1200 K loses 2500 kJ of heat to a sink at 800 K II. A heat source at 800 K loses 2000 kJ of heat to a sink at 500 K Which of the following statements is true?
A.	Process I is more irreversible than Process II
B.	Process II is more irreversible than Process I
C.	Irreversibility associated in both the processes are equal
D.	Both the processes are reversible
Answer» C. Irreversibility associated in both the processes are equal

Discussion

19.	The stroke and bore of a four stroke spark ignition engine are 250 mm and 200 mm respectively. The clearance volume is 0.001 m³. If the specific heat ratio = 1.4, the air-standard cycle efficiency of the engine is
A.	46.40%
B.
C.	56.10%
D.	58.20%
E.	62.80%
Answer» D. 58.20%

Discussion

20.	A certain amount of an ideal gas is initially at a pressure p₁ and temperature T₁ First, it undergoes a constant pressure process 1-2 such that T₂ = 3T₁ /4. Then, it undergoes a constant volume process 2-3 such that T₃ = T₁ /2. The ratio of the final volume to the initial volume of the ideal gas is
A.	0.25
B.	0.75
C.	1.0
D.	1.5
Answer» C. 1.0

Discussion

21.	A gas expands in a friction less piston-cylinder arrangement. The expansion process is very slow, and is resisted by an ambient pressure of 100 kPa. During the expansion process, the pressure of the system (gas) remains constant at 300 kPa. The change in volume of the gas is 0.01 m³. The maximum amount of work that could be utilized from the above process is.
A.	0 kJ
B.	1 kJ
C.	2 kJ
D.	3 kJ
Answer» D. 3 kJ

Discussion

22.	An ideal gas undergoes a reversible process in which the pressure varies linearly with volume. The conditions at the start (subscript 1) and at the end (subscript 2) of the process with usual notation are: p₁ = 100 kPa, V₁ = 0.2 m³ and p₂ = 200 kPa, V₂ = 0.1 m3 and the gas constant, R = 0.275 kJ/kgK. The magnitude of the work required for the process (in kJ) is______.
A.	16 kJ
B.	25 kJ
C.	18 kJ
D.	15 kJ
Answer» E.

Discussion

23.	A well insulated rigid container of volume 1 m³ contains 1.0 kg of an ideal gas [c_p = 1000 J/(kgK) and c_v = 800 J/(kgK)] at a pressure of 10⁵ Pa. A stirrer is rotated at constant rpm in the container for 1000 rotations and the applied torque is 100 Nm. The final temperature of the gas (in K) is______.
A.	1195.4 K
B.	1295 K
C.	1295.4 K
D.	2295.4 K
Answer» D. 2295.4 K

Discussion

24.	Temperature of nitrogen in a vessel of volume 2 m³ is 288 K. A U-tube manometer connected by the vessel shows a reading of 70 cm of mercury (level higher in the end open to atmosphere). The universal gas constant is 8314 J/kmol-K, atmospheric pressure is 1.01325 bar, acceleration due to gravity is 9.81 m/s² and density of mercury is 13600 kg/m³. The mass of nitrogen (in kg) in the vessel is _______.
A.	4.55
B.	5.55
C.	4.65
D.	4.59
Answer» B. 5.55

Discussion

25.	A Carnot engine (CE-1) works between two temperature reservoirs A and B, where T_A = 900 K and T_B = 500 K. A second Carnot engine (CE-2) works between temperature reservoirs B and C, where Tc = 300 K. In each cycle of CE-1 and CE-2, all the heat rejected by CE-1 to reservoir B is used by CE-2. For one cycle of operation, if the net Q absorbed by CE-1 from reservoir A is 150 MJ, the net heat rejected to reservoir C by CE-2 (in MJ) is ______.
A.	50
B.	25
C.	40
D.	30
Answer» B. 25

Discussion

26.	1.5 kg of water is in saturated liquid state at 2 bar (v_f = 0.001061 m³/kg, u_f = 504.0 kJ/kg, h_f = 505 kJ/kg). Heat is added in a constant pressure process till the temperature of water reaches 400 C (v = 1.5493 m³/kg, u = 2967.0 k J/kg, h = 3277.0 kJ/kg). The heat added (in kJ) in the process is______.
A.	4158
B.	4258
C.	5158
D.	4168
Answer» B. 4258

Discussion

27.	The enthalpy at the pump discharge (h₂) is
A.	0.33 kJ/kg
B.	3.33 kJ/kg
C.	4.0 kJ/kg
D.	33.3 kJ/kg
Answer» E.

Discussion

28.	The net work output (kJ kg¹) of the cycle is
A.	498
B.	775
C.	860
D.	957
Answer» B. 775

Discussion

29.	Heat supplied (kJ kg¹) to the cycle is
A.	2372
B.	2576
C.	2863
D.	3092
Answer» E.

Discussion

30.

Group-I shows different heat addition processes in power cycles. Likewise, Group-II shows different heat removal processes. GroupIII lists power cycles. Match items from Groups I, II and III.
Group I Group II Group III
P. Pressure constant S. Pressure constant 1. Rankine cycle
Q. Volume constant T. Volume constant 2. Otto cycle
R. Temperature U. Temperature 3. Carnot cycle
4. Diesel cycle
5. Brayton cycle

A.

P S 5, R U 3, P S 1, Q T 2

B.

P S 1, R U 3, P S 4, P T 2

C.

R T 3, P S 1, P T 4, Q S 5

D.

P T 4, R S 3, P S 1, P S 5

Answer» C. R T 3, P S 1, P T 4, Q S 5

Discussion

31.	Determine the correctness or otherwise Assertion (A) and the Reason (R). Assertion (A): In a power plant working on a Rankine cycle, the regenerative feed water heating improves the efficiency of the steam turbine. Reason (R): The regenerative feed water heating raises the average temperature of heat addition in the Rankine cycle.
A.	Both (A) and (R) are true and (R) is the correct reason for (A)
B.	Both (A) and (R) are true but (R) is NOT the correct reason for (A)
C.	Both (A) and (R) are false
D.	(A) is false but (R) is true
Answer» B. Both (A) and (R) are true but (R) is NOT the correct reason for (A)

Discussion

32.	Determine the correctness or otherwise of the following Assertion (A) and the Reason (R). Assertion (A):Condenser is an essential equipment in a steam power plant. Reason (R): For the same mass flow rate and the same pressure rise, a water pump requires substantially less power than a steam compressor.
A.	Both (A) and (R) are true and (R) is the correct reason for (A)
B.	Both (A) and (R) are true but (R) is NOT the correct reason for (A)
C.	Both (A) and (R) are false
D.	(A) is false but (R) is true
Answer» C. Both (A) and (R) are false

Discussion

33.	The crank radius of a single-cylinder IC engine is 60 mm and the diameter of the cylinder is 80 mm. The swept volume of the cylinder in cm³ is
A.	48
B.	96
C.	302
D.	603
Answer» E.

Discussion

34.	An engine working on air standard Otto cycle is supplied with air at 0.1 MPa and 35 C. The compression ratio is 8. The heat supplied is 500 kJ/kg. Property data for air: c_p = 1.005 kJ/ kgK, c_v = 0.718 kJ/kgK, R = 0.287 kJ/kgK. The maximum temperature (in K) of the cycle is ________(correct to one decimal place).
A.	1405
B.	1503.98
C.	1403.98
D.	1403
Answer» D. 1403

Discussion

35.	Air enters a diesel engine with a density of 1.0 kg/m³. The compression ratio is 21. At steady state, the air intake is 30 10³ kg/s and the net work output is 15 kW. The mean effective pressure (kPa) is_____.
A.	625
B.	525
C.	535
D.	520
Answer» C. 535

Discussion

36.	An air-standard Diesel cycle consists of the following processes: 1-2: Air is compressed isentropically. 2-3: Heat is added at constant pressure. 3-4: Air expands isentropically to the original volume. 4-1: Heat is rejected at constant volume. If and T denote the specific heat ratio and temperature, respectively, the efficiency of the cycle is
A.
B.
C.
Answer» C.

Discussion

37.	A system undergoes a State change from 1 to 2.According to the second law of thermodynamics, for the process to be feasible, the entropy change, S₂ S₁ of the system
A.	is positive or zero
B.	is negative or zero
C.	is zero
D.	can be positive, negative or zero
Answer» E.

Discussion

38.	During a non-flow thermodynamic process (1 2) execut ed by a per fect gas, t he heat interaction is equal to the work interaction (Q_1.2 = W₁₂) when the process is
A.	Adiabatic
B.	Polytropic
C.	Isothermal
D.	Isentropic
Answer» D. Isentropic

Discussion

39.	Which of the following statements are TRUE with respect to heat and work? (i) They are boundary phenomena (ii) They are exact differentials (iii) They are path functions
A.	both (i) and (ii)
B.	both (i) and (iii)
C.	both (ii) and (iii)
D.	only(iii)
Answer» C. both (ii) and (iii)

Discussion

40.	Which combination of the following statements is correct? P: A gas cools upon expansion only when its Joule-Thomson coefficient is positive in the temperature range of expansion. Q: For a system undergoing a process, its entropy remains constant only when the process is reversible. R: The work done by a closed system in an adiabatic is a point function. S: A liquid expands upon freezing when the slope of its fusion curve on pressureTemperature diagram is negative.
A.	R and S
B.	P and Q
C.	Q, R and S
D.	P, Q and R
Answer» B. P and Q

Discussion

41.	Water has a critical specific volume of 0.003155 m³/kg. A closed and rigid steel tank of volume 0.025 m³ contains a mixture of water and steam at 0.1 MPa. The mass of the mixture is 10 kg. The tank is now slowly heated. The liquid level inside the tank
A.	will rise
B.	will fall
C.	will remain constant
D.	may rise or fall depending on the amount of heat transferred
Answer» B. will fall

Discussion

42.	If one mole of H₂ gas occupies a rigid container wi t h a capaci t y of 1000 l i t er s and t he temperature is raised from 27 C to 37 C, the change in pressure of the contained gas (round off to two decimal places), assuming ideal gas behavior, is _____ Pa. (R = 8.314 J/mol.K).
A.	83.14 Pascal
B.	82.14 Pascal
C.	81.14 Pascal
D.	84.14 Pascal
Answer» B. 82.14 Pascal

Discussion

43.	If V_N and are the nozzle exit velocity and nozzle angle in an impulse turbine, the optimum blade velocity is given by
A.	V
B.	cos 2
C.	V
D.	sin 2
Answer» E.

Discussion

44.	The relationship ( T / P)_h = 0 holds good for
A.	An ideal gas at any state
B.	A real gas at any state
C.	Any gas at its critical state
D.	Any gas at its inversion point
E.	A and B both
Answer» F.

Discussion

45.	A tank of volume 0.05 m³ contains a mixture of saturated water and saturated steam at 200 C. The mass of the liquid present is 8 kg. The entropy (in kJ/kgK) of the mixture is ________ (correct of two decimal places) Property data for saturated steam and water are: At 200 C [P_sat = 1.5538 MPa] v_f = 0.001157 m³/kg, v_g = 0.12736 m³/kg s_fg = 4.1014 kJ/kgK, s_f = 2.3309 kJ/kgK
A.	s = 2.4884 kJ/kg-K
B.	s = 1.4884 kJ/kg-K
C.	s = 3.4884 kJ/kg-K
D.	s = 4.4884 kJ/kg-K
Answer» B. s = 1.4884 kJ/kg-K

Discussion

46.	In an ideal Brayton cycle, atmospheric air (ratio of specific heats, c /c_v = 1.4, specific heat at constant pressure = 1.005 kJ/kgK) at 1 bar and 300 K is compressed to 8 bar. The maximum temperature in the cycle is limited to 1280 K. If the heat is supplied at the rate of 80 MW, the mass flow rate (in kg/s) of air required in the cycle is _________.
A.	m = 18.07 kg/s.
B.	m = 108.07 kg/s.
C.	m = 1007 kg/s.
D.	m = 108kg/s.
Answer» C. m = 1007 kg/s.

Discussion

47.	A pure substance at 8 MPa and 400 C is having a specific internal energy of 2864 kJ/kg and a specific volume of 0.03432 m³/kg. Its specific enthalpy (in kJ/kg) is, ________.
A.	3239
B.	3139
C.	1339
D.	3339
Answer» C. 1339

Discussion

48.	For water at 25 C, dp_s /dT_s = 0.189 kPa/K (p_s is the saturation pressure in kPa and T_s is the saturation temperature in K) and the specific volume of dry saturated vapour is 43.38 m³/ kg. Assume that the specific volume of liquid is negligible in comparison with that of vapour. Using the Clausius-Clapeyron equation, an estimate of the enthalpy of evaporation of water at 25 C (in kJ/kg) is
A.	2445.25
B.	2553.25
C.	2543.25
D.	2443.25
Answer» E.

Discussion

49.	A rigid container of volume 0.5 m³ contains 1.0 kg of water at 120 C (v_f = 0.00106 m3/kg, v_g = 0.8908 m3/kg). The state of water is
A.	compressed liquid
B.	saturated liquid
C.	a mixture of saturated liquid and saturated vapor
D.	superheated vapor
Answer» D. superheated vapor

Discussion

50.	Which combination of the following statements is correct? The incorporation of reheater in a steam power plant: P: Always increases the thermal efficiency of the plant. Q: Always increases the dryness fraction of steam at condenser inlet. R: Always increases the mean temperature of heat addition. S: Always increases the specific work output.
A.	P and S
B.	Q and S
C.	P, R and S
D.	P, Q, R and S
Answer» C. P, R and S

Discussion

Explore topic-wise MCQs in Thermodynamics.

If the pressure at station Q is 50 kPa, the change in entropy (sQ sp) in kJ/kgK is

In order to burn 1 kilogram of CH4 completely, the minimum number of kilograms of oxygen needed is (take atomic weights of H, C and O as 1, 12 and 16 respectively)

One kg of air (R = 287 J/kgK) undergoes an irreversible process between equilibrium state 1 (20 C, 0.9 m3) and equilibrium state 2 (20 C, 0.6 m3). The change in entropy s2 s1 (in J/ kgK) is ______.

An ideal gas of mass m and temperature T1 undergoes a reversible isothermal process from an initial pressure P1 to final pressure P2. The heat loss during the process is Q. The entropy change S of the gas is

One kg of an ideal gas (gas constant R = 287 J/ kgK) undergoes an irreversible process from state-1 (1 bar, 300 K) to state-2 (2 bar, 300 K). The change in specific entropy (s2 s1) of the gas (in J/kgK) in the process is _______.

One kg of an ideal gas (gas constant, R= 400 J/ kgK; specific heat at constant volume, cp = 1000 J/kgK) at 1 bar, and 300 K is contained in a sealed rigid cylinder. During an adiabatic process, 100 kJ of work is done on the system by a stirrer. The increase in entropy of the system is _______ J/K.

A turbocharged four-stroke direct injection diesel engine has a displacement volume of 0.0259 m3 (25.9 liters). The engine has an output of 950 kW at 2200 rpm. The mean effective pressure (in MPa) is closest to

An automobile engine operates at a fuel air ratio of 0.05, volumetric efficiency of 90% and indicated thermal efficiency of 30%. Given that the calorific value of the fuel is 45 MJ/kg and the density of air at intake in 1 kg/m3, the indicated mean effective pressure for the engine is

Propane (C3H8) is burned in an oxygen atmosphere with 10% deficit oxygen with respect to the stoichiometric requirement. Assuming no hydrocarbons in the products, the volume percentage of CO in the products is___.

For a compressible fluid, sonic velocity is

An air breathing air craft is flying at an altitude where the air density is half the value at ground level. With reference to the ground level, the air- fuel ratio at this altitude will be

In a spark ignition engine working on the ideal Otto cycle, the compression ratio is 5.5. The work output per cycle (i.e., area of the P V diagram) is equal to 23.625 105 VcJ, where Vc is the clearance volume in m3. The indicated mean effective pressure is

Consider the following two processes; I. A heat source at 1200 K loses 2500 kJ of heat to a sink at 800 K II. A heat source at 800 K loses 2000 kJ of heat to a sink at 500 K Which of the following statements is true?

The stroke and bore of a four stroke spark ignition engine are 250 mm and 200 mm respectively. The clearance volume is 0.001 m3. If the specific heat ratio = 1.4, the air-standard cycle efficiency of the engine is

A certain amount of an ideal gas is initially at a pressure p1 and temperature T1 First, it undergoes a constant pressure process 1-2 such that T2 = 3T1 /4. Then, it undergoes a constant volume process 2-3 such that T3 = T1 /2. The ratio of the final volume to the initial volume of the ideal gas is

The enthalpy at the pump discharge (h2) is

The net work output (kJ kg 1) of the cycle is

Heat supplied (kJ kg 1) to the cycle is

The crank radius of a single-cylinder IC engine is 60 mm and the diameter of the cylinder is 80 mm. The swept volume of the cylinder in cm3 is

Air enters a diesel engine with a density of 1.0 kg/m3. The compression ratio is 21. At steady state, the air intake is 30 10 3 kg/s and the net work output is 15 kW. The mean effective pressure (kPa) is_____.

A system undergoes a State change from 1 to 2.According to the second law of thermodynamics, for the process to be feasible, the entropy change, S2 S1 of the system

During a non-flow thermodynamic process (1 2) execut ed by a per fect gas, t he heat interaction is equal to the work interaction (Q1.2 = W12) when the process is

Which of the following statements are TRUE with respect to heat and work? (i) They are boundary phenomena (ii) They are exact differentials (iii) They are path functions

Water has a critical specific volume of 0.003155 m3/kg. A closed and rigid steel tank of volume 0.025 m3 contains a mixture of water and steam at 0.1 MPa. The mass of the mixture is 10 kg. The tank is now slowly heated. The liquid level inside the tank

If one mole of H2 gas occupies a rigid container wi t h a capaci t y of 1000 l i t er s and t he temperature is raised from 27 C to 37 C, the change in pressure of the contained gas (round off to two decimal places), assuming ideal gas behavior, is _____ Pa. (R = 8.314 J/mol.K).

If VN and are the nozzle exit velocity and nozzle angle in an impulse turbine, the optimum blade velocity is given by

The relationship ( T / P)h = 0 holds good for

A pure substance at 8 MPa and 400 C is having a specific internal energy of 2864 kJ/kg and a specific volume of 0.03432 m3/kg. Its specific enthalpy (in kJ/kg) is, ________.

A rigid container of volume 0.5 m3 contains 1.0 kg of water at 120 C (vf = 0.00106 m3/kg, vg = 0.8908 m3/kg). The state of water is

If the pressure at station Q is 50 kPa, the change in entropy (s_Q s_p) in kJ/kgK is

In order to burn 1 kilogram of CH₄ completely, the minimum number of kilograms of oxygen needed is (take atomic weights of H, C and O as 1, 12 and 16 respectively)

One kg of air (R = 287 J/kgK) undergoes an irreversible process between equilibrium state 1 (20 C, 0.9 m³) and equilibrium state 2 (20 C, 0.6 m³). The change in entropy s₂ s₁ (in J/ kgK) is ______.

An ideal gas of mass m and temperature T₁ undergoes a reversible isothermal process from an initial pressure P₁ to final pressure P₂. The heat loss during the process is Q. The entropy change S of the gas is

One kg of an ideal gas (gas constant R = 287 J/ kgK) undergoes an irreversible process from state-1 (1 bar, 300 K) to state-2 (2 bar, 300 K). The change in specific entropy (s₂ s₁) of the gas (in J/kgK) in the process is _______.

One kg of an ideal gas (gas constant, R= 400 J/ kgK; specific heat at constant volume, c_p = 1000 J/kgK) at 1 bar, and 300 K is contained in a sealed rigid cylinder. During an adiabatic process, 100 kJ of work is done on the system by a stirrer. The increase in entropy of the system is _______ J/K.

A turbocharged four-stroke direct injection diesel engine has a displacement volume of 0.0259 m³ (25.9 liters). The engine has an output of 950 kW at 2200 rpm. The mean effective pressure (in MPa) is closest to

An automobile engine operates at a fuel air ratio of 0.05, volumetric efficiency of 90% and indicated thermal efficiency of 30%. Given that the calorific value of the fuel is 45 MJ/kg and the density of air at intake in 1 kg/m³, the indicated mean effective pressure for the engine is

Propane (C₃H₈) is burned in an oxygen atmosphere with 10% deficit oxygen with respect to the stoichiometric requirement. Assuming no hydrocarbons in the products, the volume percentage of CO in the products is___.

In a spark ignition engine working on the ideal Otto cycle, the compression ratio is 5.5. The work output per cycle (i.e., area of the P V diagram) is equal to 23.625 10⁵ V_cJ, where V_c is the clearance volume in m³. The indicated mean effective pressure is

Consider the following two processes;
I. A heat source at 1200 K loses 2500 kJ of heat to a sink at 800 K
II. A heat source at 800 K loses 2000 kJ of heat to a sink at 500 K
Which of the following statements is true?

The stroke and bore of a four stroke spark ignition engine are 250 mm and 200 mm respectively. The clearance volume is 0.001 m³. If the specific heat ratio = 1.4, the air-standard cycle efficiency of the engine is

The enthalpy at the pump discharge (h₂) is

The net work output (kJ kg¹) of the cycle is

Heat supplied (kJ kg¹) to the cycle is

The crank radius of a single-cylinder IC engine is 60 mm and the diameter of the cylinder is 80 mm. The swept volume of the cylinder in cm³ is

Air enters a diesel engine with a density of 1.0 kg/m³. The compression ratio is 21. At steady state, the air intake is 30 10³ kg/s and the net work output is 15 kW. The mean effective pressure (kPa) is_____.

A system undergoes a State change from 1 to 2.According to the second law of thermodynamics, for the process to be feasible, the entropy change, S₂ S₁ of the system

During a non-flow thermodynamic process (1 2) execut ed by a per fect gas, t he heat interaction is equal to the work interaction (Q_1.2 = W₁₂) when the process is

Which of the following statements are TRUE with respect to heat and work?
(i) They are boundary phenomena
(ii) They are exact differentials
(iii) They are path functions

Water has a critical specific volume of 0.003155 m³/kg. A closed and rigid steel tank of volume 0.025 m³ contains a mixture of water and steam at 0.1 MPa. The mass of the mixture is 10 kg. The tank is now slowly heated. The liquid level inside the tank

If one mole of H₂ gas occupies a rigid container wi t h a capaci t y of 1000 l i t er s and t he temperature is raised from 27 C to 37 C, the change in pressure of the contained gas (round off to two decimal places), assuming ideal gas behavior, is _____ Pa. (R = 8.314 J/mol.K).

If V_N and are the nozzle exit velocity and nozzle angle in an impulse turbine, the optimum blade velocity is given by

The relationship ( T / P)_h = 0 holds good for

A pure substance at 8 MPa and 400 C is having a specific internal energy of 2864 kJ/kg and a specific volume of 0.03432 m³/kg. Its specific enthalpy (in kJ/kg) is, ________.

A rigid container of volume 0.5 m³ contains 1.0 kg of water at 120 C (v_f = 0.00106 m3/kg, v_g = 0.8908 m3/kg). The state of water is