1. A closed system is one, which

A. permits the passage of energy and matter across the boundaries B. does not permit the passage of energy and matter across the boundaries C. permits the passage of energy across the boundary but does not permit the passage of matter D. permits the passage of matter across the boundary but does not permit the passage of energy

Answer - Option C
Explanation -
An isochoric process, also called a constant volume process, an isovolumetric process, or an isometric process, is a thermodynamic process during which the volume of the closed system undergoing such a process remains constant.
2. An isolated system is one, which

A. permits the passage of energy and matter across the boundaries B. permits the passage of energy only C. does not permit the passage of energy and matter across it D. permits the passage of matter only

Answer - Option C
Explanation -
Coefficient of performance of a commercially used refrigerator would be close to 1.5
3. A system comprising of a single phase, is known as

A. open system B. closed system C. homogeneous system D. heterogeneous system

Answer - Option C
Explanation -
Thermal equilibrium means that there is no heat transfer going on between the bodies, which simply means that the bodies are at the same temperature. Heat content is a whole different concept - it is the amount of heat contained in a body, which is crucially dependent on mass.
4. The characteristic of a control volume is/are

A. the volume, shape and position with respect to an observer are fixed B. material flow across the boundary C. both (a) and (b) D. none of theses

Answer - Option C
Explanation -

Newton's law of cooling applies to convective heat transfer; it does not apply to thermal radiation.Newton's law of cooling states that the rate of heat exchange between an object and its surroundings is proportional to the difference in temperature between the object and the surroundings.
5. Control volume refers to a

A. specified mass B. fixed region in the space C. closed system D. none of the above

Answer - Option B
Explanation -
Latent heat process is a process in which temperature remains constant and phase change takes place.
6. Specific heat is the amount of heat required to raise the temperature

A. by unit degree of a substance B. by unit degree of a unit mass C. of a unit mass by 10 D. none of the above

Answer - Option B
Explanation -
Ice will not sublimate at atmospheric conditions.
7. The ratio of specific heats of a gas at constant pressure and at constant volume

A. varies with temperature B. varies with pressure C. is always constant D. none of the above

Answer - Option C
Explanation -
Due to change in momentum.
8. Internal energy of a perfect gas depends upon

A. temperature only B. temperature and pressure C. temperature, pressure and specific heats D. none of the above

Answer - Option A
Explanation -
The Zeroth law of thermodynamics is the basis for measurement of temperature and setting its scale. In simple word, Zeroth law of thermodynamics says that "When two bodies are separately in thermal equilibrium with the third body, then the two are also in thermal equilibrium with each other."
9. With rise of temperature, the specific heat of water

A. increases B. decreases C. first decreases to minimum then increases D. remains constant

Answer - Option C
Explanation -
Boyle's law (sometimes referred to as the Boyle Mariotte law, or Mariotte's law) is an experimental gas law that describes how the pressure of a gas tends to increase as the volume of the container decreases.
10. For a closed system, difference between the heat added to the system and work done by the gas, is equal to the change in

A. enthalpy B. entropy C. internal energy D. temperature

Answer - Option C
Explanation -
Entropy seems to tend to some maximum value.
11. Which of the following is not an extensive property of a thermodynamic system ?

A. Total mass B. Total internal energy C. Total volume D. Temperature

Answer - Option D
Explanation -
The formulas for converting between degree
Celsius and degree Fahrenheit are:
°F = (°C – [latex]\frac{9}{5}[/latex]) + 32
°C = (°F – 32) – [latex]\frac{5}{9}[/latex]
To find the temperature when both are equal, we use an old algebra trick and just set ºF = ºC and solve one of the equations.
°C = (°C × [latex]\frac{9}{5}[/latex]) + 32
°C – (°C × [latex]\frac{9}{5}[/latex]) = 32
–4/5 × °C = 32
°C = –32 × [latex]\frac{5}{4}[/latex]
°C = –40
°F = (°F × [latex]\frac{9}{5}[/latex]) + 32
°F - (°F × [latex]\frac{9}{5}[/latex]) = 32
[latex]\frac{-4}{5}[/latex] – °F = 32
°F = – 32 – [latex]\frac{5}{4}[/latex]
°F = –40
So the temperature when both the Celsius and Fahrenheit scales are the same is -40 degrees.
12. Thermal equilibrium between two or more bodies exists, when they are brought together, there is no change in

A. density B. pressure C. temperature D. all of these

Answer - Option C
Explanation -
There are mainly three types of system:
Open System: Both mass transfer and energy transfer can take place.
Closed System: Only energy transfer can take place.
Isolated System: Both mass transfer and energy transfer can not take place.
13. The sequence of process that eventually returns the working substance to its original state, is known as

A. even B. thermodynamic cycle C. thermodynamic property D. none of these

Answer - Option B
Explanation -
Absolute pressure becomes zero when molecular momentum of the system becomes zero.
14. A system consisting of more than one phase is called

A. isolated system B. open system C. non-uniform system D. heterogeneous system

Answer - Option D
Explanation -
The zeroth law of thermodynamics states that if two thermodynamic systems each are in thermal equilibrium with a third, then they are in thermal equilibrium with each other. Accordingly, thermal equilibrium between systems is a transitive relation.
15. Kelvin-Plank’s law deals with

A. conversion of work into heat B. conversion of heat into work C. conservation of work D. conservation of heat

Answer - Option B
Explanation -
In fluid flow, the line of constant piezometric head passes through two points which have the same Velocity.
16. According to Kelvin-Plank’s statement, a perpetual motion machine of

A. first kind is possible B. first kind is impossible C. second kind is impossible D. second kind is possible

Answer - Option C
Explanation -
The boat will start moving away from the shore.
17. A perpetual motion machine of the first kind i.e. a machine which produces power without consuming any energy is

A. possible according to first law of thermodynamics B. impossible according to first law of thermodynamics C. impossible according to second law of thermodynamics D. possible according to second law of thermodynamics

Answer - Option B
Explanation -
Relative humidity is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. Relative humidity depends on temperature and the pressure of the system of interest. The same amount of water vapor results in higher relative humidity in cool air than warm air.
18. According to kinetic theory of gases, at absolute zero

A. specific heat of molecules reduces to zero B. kinetic energy of molecules reduces to zero C. volume of gas reduce to zero D. pressure of gas reduce to zero.

Answer - Option B
Explanation -
Pressure, temperature and specific volume are intensive property. Heat capacity is an extensive property. Extensive property is a property of matter that changes as the amount of matter changes.
19. In an isothermal process, internal energy

A. increases B. remains constant C. decreases D. none of the above

Answer - Option B
Explanation -
Kelvin Planck's law deals with conservation of heat into work.
20. For the same expansion ratio, work done by the gas in case of adiabatic process as compared to work done in case of isothermal process is

A. same B. more C. less D. none of the above

Answer - Option C
Explanation -
Kaplan turbine is used for low head. Low head turbines are those turbines with a head of 20 metres (66 ft) or less to produce energy.

1. In isothermal expansion, work done by gas depends upon

A. atomicity of gas only B. expansion ratio only C. adiabatic index D. both (a) and (b)

Answer - Option D
Explanation -
An isolated system does not exchange energy or matter with its surroundings. A system and its environment put together constitute an isolated system.
2. A process, in which no heat is supplied or rejected from the system and entropy is not constant, is called

A. isothermal B. isentropic C. polytropic D. hyperbolic

Answer - Option C
Explanation -
[latex]\frac{dT}{ds} = \frac{T}{{C}_{v}}[/latex]
3. A process, in which the working substance neither receives nor gives out heat to its surroundings during its expansion or contraction, is called

A. isothermal process B. isentropic process C. polytropic process D. adiabatic process

Answer - Option D
Explanation -
Zeroth law of thermodynamics forms the basis of measurement of temperature. It states that when two bodies are in thermal equilibrium with a third body, then they are also in thermal equilibrium with each other.
4. If [latex]{v}_{1}[/latex] is volume at the begining and [latex]{v}_{2}[/latex] is volume at the end of expansion, then expansion ratio (r) is given by

A. [latex]\frac{{v}_{1}}{{v}_{2}}[/latex] B. [latex]\frac{{v}_{2}}{{v}_{1}}[/latex] C. [latex]\frac{{v}_{1} + {v}_{2}}{{v}_{1}}[/latex] D. [latex]\frac{{v}_{1} + {v}_{2}}{{v}_{2} - {v}_{1}}[/latex]

Answer - Option B
Explanation -
The first law of thermodynamics makes the use of the key concepts of internal energy, heat and system work.
[latex]\triangle U = Q - W[/latex]
[latex]\triangle U \rightarrow Change in internal energy[/latex]
[latex]\triangle Q\rightarrow Heat added to the system[/latex]
[latex]\triangle W \rightarrow Work done by system[/latex]
5. The net work done in a poly-tropic process is given by

A. [latex]\frac{{p}_{1}{v}_{1}- {p}_{2}{v}_{2}}{(n - 1)}[/latex] B. [latex]\frac{{p}_{2}{v}_{2}- {p}_{1}{v}_{1}} {(n - 1)}[/latex] C. [latex]\frac{{p}_{1}{v}_{1}- {p}_{2}{v}_{2}} {n}[/latex] D. [latex]\frac{{p}_{2}{v}_{2}- {p}_{1}{v}_{1}} {n}[/latex]

Answer - Option A
Explanation -
Otto cycle is an idealized thermodynamic cycle which consists of two isentropic (reversible adiabatic) processes and two isochoric (constant volume) processes.
6. The polytropic index (n) is given by

A. [latex]\frac{log(\frac{{p}_{2}}{{p}_{1}})}{log(\frac{{v}_{1}}{{v}_{2}})}[/latex] B. [latex]\frac{log(\frac{{v}_{1}}{{v}_{2}})}{log(\frac{{p}_{1}}{{p}_{2}})}[/latex] C. [latex]\frac{log(\frac{{p}_{1}}{{p}_{2}})}{log(\frac{{v}_{1}}{{v}_{2}})}[/latex] D. None of the above

Answer - Option A
Explanation -
Control volume: Control volume is a volume fixed in space or moving with constant velocity through which the fluid (gas or liquid) flows.
7. In a throttling process

A. W = 0 B. E = 0 C. H = 0 D. all of the above

Answer - Option D
Explanation -
Mass and volume are extensive properties. Intensive properties are those properties that does not depend on the system size or the amount of material in the system, such as density, pressure etc.
8. In a reversible poly-tropic process

A. enthalpy remains constant B. entropy remains constant C. some heat transfer occurs D. internal energy remains constant

Answer - Option C
Explanation -
If temperature increases, the kinematic viscosity of gases increases.
9. In the poly-tropic equation, [latex]p{V}^{n}[/latex] = constant, if value of n is infinite, then process is called

A. constant pressure process B. constant volume process C. constant temperature process D. none of

Answer - Option B
Explanation -
First law of thermodynamics deals with conservation of energy. The law of conservation of energy states that the total energy of an isolated system is constant; energy can be transformed from one form to another, but can be neither created nor destroyed.
10. In the poly-tropic process equation, [latex]p{V}^{n}[/latex] = constant, if n = 0, the process is called

A. constant pressure process B. constant volume process C. constant temperature process D. none of these

Answer - Option A
Explanation -
Boyle's law: According to Boyle's law, the pressure (P) of a given mass of gas is inversely proportional to its volume (V), provided that the temperature of the gas remains constant.
11. In the poly-tropic process equation, [latex]p{V}^{n}[/latex] = constant, if n = 1, the process is called

A. constant pressure process B. constant volume process C. constant temperature process D. none of these

Answer - Option C
Explanation -
Heat is closely related with temperature.
12. In the polytropic process equation, [latex]p{V}^{n}[/latex] = constant, the process will be adiabatic, if n in the equation is

A. 0 B. 1 C. [latex]\gamma[/latex] D. infinite

Answer - Option C
Explanation -
[latex]\frac{{T}_{1} + {T}_{2}}{{T}_{1}} = \frac{{T}_{1} - {T}_{2}}{{T}_{1}}[/latex][Both engines equally efficient]
[latex]\Rightarrow \frac{900 + {T}_{2}}{900} = [latex]\frac{{T}_{2} - 400}{{T}_{2}}[/latex]
[latex]\Rightarrow {T}_{2} = 600 Kelvin[/latex]
13. In a reversible adiablatic process, the ratio of [latex]\frac{{T}_{1}}{{T}_{2}}[/latex] is equal to

A. [latex]({\frac{{p}_{1}}{{p}_{2}}})^{\frac{y - 1}{y}}[/latex] B. [latex]({\frac{{p}_{2}}{{p}_{1}}})^{\frac{y - 1}{y}}[/latex] C. [latex]({\frac{{V}_{1}}{{V}_{2}}})^{\frac{y - 1}{y}}[/latex] D. [latex]({\frac{{V}_{2}}{{V}_{1}}})^{\frac{y - 1}{y}}[/latex]

Answer - Option C
Explanation -
Work done in free expansion process is always zero.
14. A reversible process

A. must pass through a continuous series of equlibrioum states B. leaves no history of the events in surroundings. C. must pass through the same states on the reversed path as on the forward path. D. all of these.

Answer - Option D
Explanation -
Internal energy of an ideal gas depends only on temperature, not on pressure and volume.
15. Isentropic flow is

A. reversible adiabatic flow B. irreversible adiabatic flow C. friction less fluid flow D. none of the above.

Answer - Option A
Explanation -
An isotropic process is an idealized thermodynamic process that is both adiabatic and reversible. The work transfers of the system are friction less and there is no transfer of heat or matter.
16. Non quasi-static process is

A. free expansion of gas B. expansion of a gas in a cylinder under constant pressure C. rapid compression of a gas in a cylinder. D. gradual compression of a gas in a cylinder

Answer - Option A
Explanation -
Economiser: Economizers are generally heat ex changers which are designed to exchange heat with the fluid, generally water.
17. For an ideal gas, the change in enthalpy ([latex]\triangle[/latex]H) for an elemental change in temperature [latex]\triangle[/latex]T is given by

A. [latex]{C}_{p}\triangle T[/latex] B. [latex]{C}_{v}\triangle T[/latex] C. [latex]\frac{{C}_{p}}{{C}_{v}}\triangle T[/latex] D. [latex]\frac{{C}_{v}}{{C}_{p}}\triangle T[/latex]

Answer - Option A
Explanation -
Pelton wheel turbine, turgo turbines are high head turbine.
18. One hundredth of a kilogram of air is compressed in a piston-cylinder device. At an instant of time when T = 400 K, the rate at which work is being done on the air is 8.165 kW, and heat is being removed at a rate of 1.0 k W, the rate of temperature rise will be

A. 10 K/s B. 100 K/s C. 1000 K/s D. 10000 K/s

Answer - Option C
Explanation -
du = [latex]\delta Q – \delta W [/latex]
[latex]\rightarrow[/latex]du = Tds – pdv
[latex]\rightarrow[/latex] Tds = du + pdv q1
19. For which of the following situations, zeroth law of thermodynamics will not be valid ?

A. 50 cc of water at 25º C are mixed with 150 cc of water at 25º C B. 500 cc of milk at 15º C are mixed with 100 cc of water at 15º C C. 5 kg of wet steam at 100º C is mixed with 50 kg of dry and saturated steam at 100º C D. 10 cc of water at 20º C are mixed with 10 cc of sulphuric acid at 20º C.

Answer - Option D
Explanation -
PMM1 is closely related with first law of thermodynamics. It violates the first law of thermodynamics.

20. Figure shows a vessel divided into two parts by a diaphragm. The space A contains a gas and space B is evacuated. These two spaces are separated by a diaphragm. Now if the diaphragm is punctured, the gas will expand into the evacuated space B. Which of the following statement is invalid ?

A. A free expansion is a non-quasi static process B. The pressure and volume of gas are not related through the equation of states C. The process is irreversible D. The energy is transferred to the system.

Answer - Option D
Explanation -
Isolated system is a system that can not exchange either energy or matter outside the boundaries of the system.

1. In a thermodynamic system, a process in which volume remains constant is called _____ process.

A. isobaric B. isometric C. adiabatic D. isotropic

Answer - Option B
Explanation -
In heat transfer analysis, thermal diffusivity is the thermal conductivity divided by density and specific heat capacity at constant pressure. It measures the rate of transfer of heat of a material from the hot side to the cold side. It has the SI derived unit of m²/s.
[latex]\alpha = \frac{heat conducted}{heat stored} = \frac{k}{\rho {c}_{p}}[/latex]
2. Coefficient of performance of a commercially used refrigerator would be close to

A. 40 % B. 85 % C. 15 D. 35

Answer - Option C
Explanation -
Fins are used to increase heat transfer rate.
3. In a thermodynamic system, thermal equilibrium is achieved when two bodies reach

A. same thermal energy B. same entropy C. same temperature D. same molecular energy

Answer - Option C
Explanation -
Heat is mainly transferred by conduction, convection and radiation in Boiler furnaces.
4. A hot body follows Newton's law of cooling. Typical temperature-time graph of the cooling body would be

A.

B.

C.

D.

Answer - Option D
Explanation -
Heat can be transferred from one place to another by three methods: conduction in solids, convection of fluids (liquids or gases), and radiation through anything that will allow radiation to pass. The method used to transfer heat is usually the one that is the most efficient.
5. Consider the following graph :

Which portion represents the 'Latent heat of fusion'?

A. OA B. AB C. BC D. CD

Answer - Option B
Explanation -
Collisions and diffusion.
6. Which of the following does not sublimate?

A. Ice B. Ammonium chloride C. Naphthalene D. Camphor

Answer - Option A
Explanation -
Heat transfer between two bodies only takes place when temperature of one body is different from temperature of other body.
7. The pressure exerted on the walls of a container by a gas is due to the fact that Gas molecules :

A. Stick to the walls of the container B. Lose their kinetic energy C. Get accelerated towards the wall D. Change their momentum due to collision with the wall.

Answer - Option D
Explanation -
Stephan Boltzmann law is applicable to black body, theoretical surfaces that absorb all incident heat radiation.
8. Zeroth Law of thermodynamics forms the basis of measurement.

A. Pressure B. Temperature C. Work D. Momentum

Answer - Option B
Explanation -
Heat transfer takes place in boiler furnaces through three modes, namely conduction, convection and radiation.
9. Boyle's law states that:

A. The pressure of a gas varies directly with temperature at constant volume i.e. P[latex]\alpha[/latex]T. B. The product of pressure and volume of a given mass of a gas is constant at constant C. The volume of a gas varies directly with temperature at constant pressure i.e. V[latex]\alpha[/latex]T. D. The pressure of a gas varies directly with volume at constant temperature i.e. P[latex]\alpha[/latex]V.

Answer - Option B
Explanation -
Overall heat transfer concept is used in the combined mode of heat transfer of conduction and convection.
10. The entropy of universe tends to be :

A. Minimum B. Zero C. Average D. Maximum

Answer - Option D
Explanation -
Unit of thermal conductivity in S.I. unit i W/mk.
11. At what temperature, both Celsius and Fahrenheit scales will show the identical readings ?

A. 100° B. -40° C. 0° D. 40°

Answer - Option C
Explanation -
An object that absorbs all radiation falling on it, at all wavelength is called a black body.
12. A closed thermodynamic system is one in which

A. There is no energy or mass transfer across the boundary B. There is no mass transfer, but energy transfer exists C. There is no energy transfer, but mass transfer exists D. Both energy and mass transfer take place across the boundary, but mass transfer is controlled by valves

Answer - Option B
Explanation -
Fourier's law of heat conduction is applicable only for one dimensional cases.
13. Pressure reaches a value of absolute zero

A. at a temperature of –273 K B. under vacuum condition C. at the earth's centre D. when molecular momentum of system becomes zero

Answer - Option D
Explanation -
When the body is under thermal equilibrium, then its absorptivity is equal to its emissivity.
14. Zeroth Law of Thermodynamics states that

A. Two thermodynamic systems are always in thermal equilibrium with each other B. If two systems are in thermal equilibrium, then the third system will also be in thermal equilibrium C. Two systems not in thermal equilibrium with a third system will also not be in thermal equilibrium with each other D. When two systems are in thermal equilibrium with a third system they are in thermal equilibrium with each other

Answer - Option B
Explanation -
Metallic bonds are made from a lattice of irons in a 'cloud' of free electrons. These free electrons are responsible for the ability of metals to conduct heat.
15. In fluid flow, the line of constant piezometric head passes through two points which have the same

A. Elevation B. Pressure C. Velocity D. Velocity potential

Answer - Option C
Explanation -
Heat conduction in gases is due to elastic impact of molecules.
16. A man is standing on a boat in still water. If he walks in the boat towards the shore, the boat will

A. move away from the shore B. remain stationary C. move towards the shore D. Sink

Answer - Option A
Explanation -
In solids, flow of heat is through conduction heat transfer method.
17. Relative Humidity is the percentage of the

A. absolute humidity value to the amount of humidity actually present B. increase of humidity/absolute humidity C. amount of humidity actually present to the absolute humidity D. None of these

Answer - Option D
Explanation -
Black body is that type of body which absorbs all radiant energy at all wavelengths.
18. Which of the following is an extensive property?

A. Pressure B. Heat capacity C. Temperature D. Specific volume

Answer - Option B
Explanation -
Convection is the heat transfer due to bulk movement of molecules within fluids such as gases and liquids.
19. Kelvin Planck’s law deals with

A. Conservation of heat B. Conservation of heat C. Conservation of heat into work D. Conservation of work into heat

Answer - Option C
Explanation -
Solid ice has highest thermal conductivity than boiling water, steam and rain water. Thermal conductivity is evaluated primarily in terms of the Fourier's law for heat conduction.
20. Turbine used for low head is

A. Kaplan turbine B. Francis turbine C. Pelton Wheel turbine D. Propeller turbine

Answer - Option A
Explanation -
Lorentz number is defined as the ratio of thermal conductivity to electrical conductivity at a given temperature.
L = [latex]\frac {k}{\sigma T}[/latex]
Where,
L = Lorentz number
[latex]\sigma[/latex] = electrical conductivity
K = Thermal conductivity

1. A system and its environment put together constitute

A. An adiabatic system B. An isolated system C. A segregated system D. A homogeneous system

Answer - Option B
Explanation -
Effectiveness of fin: Effectiveness of fin is defined as the ratio of actual heat transfer that takes place from the fin to the heat that would be dissipated from the same surfaces area without fin. It will be maximum with free convection
2. Slope of constant volume line on temperature entropy diagram is given by

A. [latex]\frac{{C}_{p}}{T}[/latex] B. [latex]\frac {T}{{C}_{p}}[/latex] C. [latex]\frac{{C}_{v}}{T}[/latex] D. [latex]\frac {T}{{C}_{v}}[/latex]

Answer - Option D
Explanation -
Radiation is the heat transfer due to emission of electromagnetic waves. From boiler furnace to water wall, radiation modes of heat transfer takes place.
3. Zeroth law of thermodynamics forms the basis of measurement of

A. Pressure B. Temperature C. Heat exchange D. Work

Answer - Option B
Explanation -
Heat pipe acts as a superconductor. Heat pipes are transport mechanisms that can carry heat fluxes ranging from 10 w/[latex]{cm}_{2}[/latex] to 20 kw/[latex]{cm}_{2}[/latex] at nearly the speed of sound (340 m/sec.)
4. Internal energy is defined by

A. Zeroth law of thermodynamics B. First law of thermodynamics C. Second law of thermodynamics D. Law of entropy

Answer - Option A
Explanation -
Ice is very close to black body because ice is a very good absorb-er of radiation outside the visible region.
5. The given P-V diagram indicates following cycle

A. Carnot cycle B. Otto cycle C. Diesel cycle D. Dual cycle

Answer - Option B
Explanation -
Because air has lowest value of thermal conductivity among-st given options.
6. Control volume refers to

A. A fixed region in space B. A specified mass C. An isolated system D. A reversible process only

Answer - Option A
7. All of the following are intensive properties EXCEPT

A. Mass B. Density C. Pressure D. Temperature

Answer - Option A
8. Kinematic viscosity of gases on increase of temperature

A. Decreases B. Increases C. Remains the same D. First decreases then increases

Answer - Option B
9. First law of thermodynamics deals with

A. Conservation of heat B. Conservation of momentum C. Conservation of mass D. Conservation of energy

Answer - Option D
10. An isothermal process is governed by

A. Boyle’s law B. Charle’s law C. Gay-lussac’s law D. Avogadro’s law

Answer - Option A
11. Heat is closely related with

A. Energy B. Temperature C. Entropy D. Enthalpy

Answer - Option B
12. An engine operates between temperature limits of 900 K and T2: and another between T2 and 400 K. For both the engines to be equally efficient. T2 should be equal to

A. 600 K B. 650 K C. 625 K D. 700 K

Answer - Option A
13. Work done in a free expansion process is

A. Zero B. Positive C. Negative D. Maximum

Answer - Option A
14. The internal energy of an ideal gas is

A. A function of temperature only B. A function of pressure C. A function of volume D. Both pressure and volume

Answer - Option A
15. The process in which no heat enters or leaves the system is called

A. Isobaric B. Isothermal C. Isentropic D. Isochoric

Answer - Option C
16. Economiser used in power plants is used to heat

A. flue gases B. intake air C. steam D. feed water

Answer - Option D
17. Which of the following is a high head turbine

A. Propeller turbine B. Francis turbine C. Kaplan turbine D. Pelton wheel turbine

Answer - Option D
18. Which one of following expression is true for Tds equation

A. du – PdV B. du + PdV C. du – VdP D. du + VdP

Answer - Option B
9. PMM 1 is closely related with

A. First law of thermodynamics B. Second law of thermodynamics C. Third law of thermodynamics D. Zeroth law of thermodynamics

Answer - Option A
20. Isolated system indicates

A. Mass of substance cross the boundary B. Energy of substance cross the boundary C. Both mass and energy of substance cross the boundary D. Both mass and energy substance does not cross the boundary

Answer - Option D

1. The thermal diffusivity of a substance is given by :

A. [latex]\frac{K \rho}{C}[/latex] B. [latex]\frac {K}{C \rho}[/latex] C. [latex]\frac{K C}{\rho}[/latex] D. [latex]\frac{C \rho}{K}[/latex]

[Where K = Thermal conductivity; p = Mass density; C = Specific heat]
Answer - Option B
2. Fins are provided on heat transferring surface in order to increase :

A. Heat transfer area B. Heat transfer coefficient C. Temperature gradient D. Mechanical strength of the equipment

Answer - Option A
3. Heat is mainly transferred by conduction, convection and radiation in

A. Insulated pipes carrying hot water B. Refrigerator freezer coil C. Boiler furnaces D. Condensation of steam in a condenser

Answer - Option C
4. Heat transfer in liquids and gases is essentially due to

A. Conduction B. Convection C. Radiation D. Conduction and Radiation put together

Answer - Option B
5. In which of the following mechanisms, is heat conducted in liquid and gas

A. Lattice vibration B. Transportation of free electrons C. Collisions and diffusion D. No heat conducted

Answer - Option C
6. An essential requirement for the transfer of heat from one body to another body is that

A. Both bodies must be solids B. Both bodies must be in contact C. Temperatures of the two bodies must be different D. Temperatures of the two bodies must be same

Answer - Option C
7. Stefen Boltzman law is applicable to

A. Gray body B. White body C. Black body D. Blue body

Answer - Option C
8. Heat is transferred by conduction, convection and radiation in

A. Insulated pipe carrying hot water B. Refrigerator freezer coils C. Melting of ice D. Boiler furnaces

Answer - Option D
9. The concept of overall heat transfer is used in the heat transfer in the case of

A. Conduction B. Convection C. Radiation D. Combined mode of heat transfer of conduction and convection

Answer - Option D
10. The unit of thermal conductivity in S.I. unit is

A. W/mK B. [latex]{W}^{2}[/latex] /mK C. W/[latex]{m}^{2}k[/latex] D. W/m

Answer - Option A
11. All radiations in a black body are

A. Reflected B. Refracted C. Transmitted D. Absorbed

Answer - Option D
12. Fourier’s law of heat conduction gives the heat flow for

A. Irregular surfaces B. Non-uniform temperature surfaces C. One dimensional cases only D. Two dimensional cases only

Answer - Option C
13. Absorptivity of a body is equal to its emissivity

A. For a polished body B. Under thermal equilibrium C. At one particular temperature D. At shorter wavelengths

Answer - Option B
14. Metals are good conductor of heat because

A. Their atoms collide frequently B. Their atoms are relatively far apart C. They contain free electron D. They have high density

Answer - Option A
15. Heat conduction in gases is due to

A. Electromagnetic waves B. Motion of electrons C. Mixing motion of the different layers of the gas D. Elastic impact of molecules

Answer - Option D
16. The heat flow through solids only by

A. Conduction B. Convection C. Radiation D. Does not flow

Answer - Option A
17. A perfect black body is

A. One which absorbs total radiant energy B. Black in colour C. One which does not reflect the radiant energy D. One which absorbs all radiant energy at all wavelengths

Answer - Option D
18. Heat transfer by molecular collision in

A. Conduction B. Convection C. Radiation D. Scattering

Answer - Option B
19. Which one of the following have a highest thermal conductivity

A. Boiling water B. Steam C. Solid ice D. Rain water

Answer - Option C
20. The ratio of thermal conductivity to electrical conductivity is equal to

A. Prandtl number B. Schmidt number C. Lorentz number D. Lewis number

Answer - Option C

1. The effectiveness of a fin will be maximum in an environment with

A. Free convection B. Forced convection C. Radiation D. Convection and radiation

Answer - Option A
2. Which one of the following modes of heat transfer would takes place predominantly from boiler furnace to water wall

A. Convection B. Conduction C. Radiation D. Conduction and Convection

Answer - Option C
3. Heat pipe is widely used now a days, use

A. It acts as an insulator B. It acts as conductor and insulator C. It acts as a superconductor D. It acts as afin

Answer - Option C
4. Ice is very close to a

A. Gray body B. Black body C. White body D. Specular body

Answer - Option B
5. In which one of the following materials is the heat propagation minimum due to conduction heat transfer?

A. Lead B. Copper C. Water D. Air

Answer - Option D
6. Assume that a 1 ton air conditioner is required to cool a room of size 14' × 14' × 14'. How many 1 ton ACs would be required for a hall of size of 24' × 24' of t he same roof height as that of t he previous room?

A. 2 B. 3 C. 4 D. 5

Answer - Option B
Explanation -
1 tonne AC's required
for size of room = 14 × 14 × 14 = 2744 unit
Now, for size of room = 24 × 24 × 14 = 8064 unit
So, number of tonne of AC's required
for this = [latex]\frac{8064}{2744}[/latex] = 2.938 = 3 unit(Approx)
7. Efficiency of Carnot cycle is:

A. [latex]1 - \frac{{Q}_{1}}{{Q}_{1} + {Q}_{2}}[/latex] B.[latex]1 - \frac{{T}_{1}}{{T}_{2}}[/latex] C. [latex]1 - \frac{{T}_{1}}{{T}_{1} + {T}_{2}}[/latex] D. [latex]1 - \frac{{Q}_{1}}{{Q}_{2}}[/latex]

Answer - Option B
Explanation -
[latex]{T}_{2}[/latex] is source temperature
[latex]{T}_{1}[/latex] is sink temperature
Carnot cycle efficiency is a function of temperature limits only.
i.e, [latex]\eta = 1 - \frac{{T}_{1}}{{T}_{2}}[/latex]
8. In a building, water is to be pumped to a height of 10m at the rate of 1 litre/second. Power requirement would be approx: (Take ‘g’ 10 m/[latex]{sec}^{2}[/latex])

A. 10 Watts B. 100 Watts C. 500 Watts D. 1 kW

Answer - Option B
Explanation -
Given:
Height = 10 m
Discharge(Q) Rate = 1 litre/second
= [latex]\frac{1}{1000} {m}^{3}/sec[/latex]
Here, Power = [latex]\frac{Work}{1000} = \frac{mgh}{t} = Qgh[/latex]
[latex]\frac{PVgh}{t} = PQgh[/latex]
[latex]1000 * \frac{1}{1000} * 10 * 10[/latex]
= 100 watt
9. Which law of thermodynamics defines Entropy?

A. Zeroth B. First C. Second D. Third

Answer - Option C
Explanation -
The second law of thermodynamics states that the state of entropy of the entire universe, as an isolated system, will always increase overtime. The second law also states that the changes in the entropy in the universe can never be negative.
10. If a system in equilibrium is subjected to a change of concentration; temperature or pressure, the equilibrium shifts in a direction that tends to undo the effect of the change imposed. This is known as:

A. Le Chatelier's Principle B. Law of Mass Action C. Vander Waals Principle D. None of these

Answer - Option A
Explanation -
Le-chatelier's principle: A principle stating that if a constraint (such as a change in pressure, temperature or concentration of a reactant) is applied to a system in equilibrium the equilibrium will shift so as to tend to counteract the effect of the constraint.
11. 6. The value of [latex]\Sigma \frac{dQ}{T}[/latex] for an irreversible process is:

A. Less than zero B. Greater than zero C. Equal to zero D. Any one of these

Answer - Option A
Explanation -
Value of [latex]\Sigma \frac{dQ}{T}[/latex] for an irreversible process is less than zero.
12. Which of the following cycles is used in thermal power plants ?

A. Rankine B. Carnot C. Otto D. Joule

Answer - Option A
Explanation -
Rankine cycle is used in thermal power plants.
13. The characteristic equation of Gases PV = nRT holds good for :

A. Mono-atomic Gases B. Diatomic Gases C. Ideal Gases D. Real Gases

Answer - Option C
Explanation -
Ideal Gas equation is given by PV = nRT
14. For an Ideal Gas, the change in Enthalpy ([latex]\triangle[/latex]H) for an elemental change in temperature ([latex]\triangle[/latex]T) is given by: (where [latex]{C}_{p}[/latex] = Heat capacity at Constant Pressure; [latex]{C}_{v}[/latex] = Heat capacity at Constant Volume)

A. [latex]{C}_{v} \triangle T[/latex] B. [latex]\frac {{C}_{p}}{{C}_{v}} \triangle T[/latex] C. [latex]\frac {{C}_{v}}{{C}_{p}} \triangle T[/latex] D. [latex]{C}_{p} \triangle T[/latex]

Answer - Option D
Explanation -
The change in enthalpy( [latex]\triangle[/latex] H) is given by, [latex]{C}_{p} \triangle T[/latex].
15. A perfect gas at 27 °C is heated at constant pressure till its volume is doubled. The final temperature is :

A. 54°C B. 108°C C. 327°C D. 600°C

Answer - Option C
Explanation -
[latex]{T}_{1}[/latex] = 27 + 273 = 300K
[latex]{V}_{1}[/latex] = V
[latex]{V}_{2}[/latex] = 2V
[latex]{T}_{2}[/latex] = ?
By using,
[latex]\frac{{P}_{1}{V}_{1}}{{T}_{1}} = \frac{{P}_{2}{V}_{2}}{{T}_{2}} [/latex]
Given, [latex]{P}_{1} = {P}_{2}[/latex]
So, [latex]\Rightarrow \frac{{V}_{1}}{300} = \frac{2V}{{T}_{2}} [/latex]
[latex]{T}_{2} [/latex] = 300 × 2 = 600K = (600 – 273) °C = 327°C
16. Zeroth law of thermodynamics is the basis of

A. Pressure measurement B. Temperature measurement C. Density measurement D. Viscosity measurement

Answer - Option B
Explanation -
The zeroth law is incredibly important as it allows us to define the concept of temperature scale. If two systems are each in thermal equilibrium with third, they are also in thermal equilibrium with each other.
17. A process in which no heat crosses the boundary of the system is called

A. Ideal process B. Adiabatic process C. Isothermal process D. Isobaric process

Answer - Option B
Explanation -
In thermodynamics, an adiabatic process is one that occurs without transfer of heat or mass of substances between a thermodynamic system and its surroundings. In an adiabatic process, energy is transferred to the surrounding only as work.
18. The enthalpy of a substance is defined as

A. h = pv+RT B. h = u+pT C. h = u+pv D. h = u-pv

Answer - Option C
Explanation -
Enthalpy of a system is equal to the system’s internal energy plus the product of its pressure and volume.
h = u + pv
19. Cyclic integral of any property is

A. 0 B. 1 C. Infinite D. 2

Answer - Option A
Explanation -
Cyclic integral of any property is zero
20. The machine which violates the first law of thermodynamics is known as

A. PMM -I B. PMM -II C. PMM -III D. Heat engine

Answer - Option A
Explanation -
PMM-I [latex]\Rightarrow[/latex] PMM-I stands for perpetual motion machine-I . It is a hypothetical machine which can produce useful energy (work) without any source or which can produce more energy than consumed. It violates the first law of thermodynamics.

1. The device in which the work is done by the fluid at the expense of its enthalpy is known as

A. Compressor B. Throttling device C. Turbine D. Heat exchanger

Answer - Option C
Explanation -
Turbine is a device designed to do work at the expense of a decrease in either the enthalpy of a fluid or the kinetic energy of the fluid or both.
2. A device which increases the velocity of a fluid at the expense of its pressure drop is known as

A. Diffuser B. Nozzle C. Throttling device D. Heat transfer

Answer - Option B
Explanation -
Nozzle increases the velocity of the fluid at the expense of its pressure drop
3. The Prandtl number for liquid, which has velocity boundary layer much thicker than thermal boundary layer, is

A. [latex]{P}_{r} \gg 1[/latex] B. [latex]{P}_{r} \ll 1[/latex] C. [latex]{P}_{r} \approx 1[/latex] D. [latex]{P}_{r} = 0[/latex]

Answer - Option A
Explanation -
Prandtl number for liquid, which has velocity boundary layer much thicker than ther mal boundary layer, is given by “[latex]{P}_{r} \gg 1[/latex]”.
4. A fluid flow in which the density of the fluid does not change during flowing is called as

A. In compressible B. Uniform C. Compressible D. Non-linear

Answer - Option A
Explanation -
Incompressible fluid is a fluid whose density does not change when the pressure changes. In in compressible flow, the material density is constant within a fluid parcel.
5.The formation of bubbles of vapor in a flowing fluid is called as

A. Cavitation B. Corrosion C. Gasification D. Boiling

Answer - Option A
Explanation -
Formation of bubbles of vapour in a flowing fluid is called as cavitation
6. A large body of infinite heat capacity is known as

A. Thermal Energy Reservoir (TER) B. Mechanical energy reservoir (MER) C. Thermometer D. Heat pump

Answer - Option A
Explanation -
Thermal Energy Reservoir: A thermal energy reservoir (TER) is defined as a large body of infinite heat capacity, which is capable of absorbing or rejecting an unlimited quantity of heat without suffering appreciable changes in its thermodynamic co-ordinates
7. "Heat always flows from a body at a higher temperature to a body at a lower temperature" is the statement of

A. First law of thermodynamics B. Second law of thermodynamics C. Third law of thermodynamics D. Zeroth law of thermodynamics

Answer - Option B
Explanation -
Second law of thermodynamics states that heat flows naturally from an object at a higher temperature to an object at a lower temperature, and heat does not flow in the opposite direction of its own.
8. The network output for any heat engine is given by

A. [latex]{Q}_{L} - {Q}_{H}[/latex] B. [latex]{Q}_{L} + {Q}_{H}[/latex] C. [latex]{Q}_{H} - {Q}_{L}[/latex] D. [latex]2{Q}_{L}[/latex]

[latex]{Q}_{H}[/latex] = Magnitude of heat transfer between heat engine and source.
[latex]{Q}_{L}[/latex] = magnitude of heat transfer between heat engine and sink.
Answer - Option C
Explanation -
[latex]{Q}_{H} - {Q}_{L}[/latex]
where,
[latex]{Q}_{H}[/latex] = Magnitude of heat transfer between heat engine and source.
[latex]{Q}_{L}[/latex] = magnitude of heat transfer between heat engine and sink.
9. A cyclic device which produces work continuously at the expense of heat input is known as

A. Refrigerator B. Heat pump C. Heat engine D. Throttling

Answer - Option C
Explanation -
Heat Engine: A heat engine is a device that converts chemical energy to heat or thermal energy and then to mechanical energy or to elect rical energy. It is a cyclic device which produces work continuously at the expense of heat input.
10. A liquid forms an interface with another liquid or gas; the surface energy per unit area of the interface is known as

A. Surface tension B. Specific energy C. Specific heat D. Suction energy

Answer - Option A
Explanation -
Surface Tension: Surface tension is measured as the energy required to increase the surface area of a liquid by a unit of area. The surface tension of a liquid results from an imbalance of intermolecular attractive forces, the cohesive forces between the molecules.
11. According to Darcy's law, for laminar flow in a saturated soil, the rate of flow is proportional to the

A. Cross sectional area B. Hydraulic gradient C. Coefficient of permeability D. Porosity of the soil

Answer - Option B
Explanation -
Hydraulic Gradient: The hydraulic gradient is a vector gradient between two or more hydraulic head measurements over the length of the flow path. According to darcy’s law, for laminar flow in a saturated soil, the rate of flow is proportional to hydraulic gradient.
12. The efficiency of perpetual motion machine-ll (PMM-II) is

A. 0% B. 50% C. 75% D. 100%

Answer - Option D
Explanation -
P M M – II Machines are those machines which violate the second law of thermodynamics because such machines will absorb continuously heat energy from a single thermal reservoir and will convert the aborbed heat energy completely into work energy.
P M M II efficiency is approximately 100%

13. A thermal energy reservoir that supplies the heat is known as

A. Refrigerator B. Source C. Sink D. Heat engine

Answer - Option B
Explanation -
Source is a thermal energy reservoir that supplies the heat and Sink is a thermal energy reservoir that receives the heat.
14. Thermal efficiency of heat engine may be defined as

A. [latex]1 - (\frac{{Q}_{2}}{{Q}_{1})}[/latex] B. [latex]2 - \frac{{Q}_{1}}{{Q}_{2}}[/latex] C. [latex]1 *(\frac{{Q}_{1}}{{Q}_{2}})[/latex] D. [latex]4 - \frac{{Q}_{1}}{{Q}_{2}}[/latex]

Where, [latex]{O}_{1}[/latex] = magnitude of heat transfer between heat engine and source
Where, [latex]{Q}_{2}[/latex] = magnitude of heat transfer between heat engine and sink.
Answer - Option A
Explanation -
Thermal efficiency of Heat engine,
i.e, [latex]\eta = \frac{{W}_{net}}{{Q}_{1}} = \frac{{Q}_{net}}{{Q}_{1}} = 1 - \frac{{Q}_{2}}{{Q}_{1}}[/latex]
where, [latex]{Q}_{2} \Rightarrow [/latex] Heat rejected
[latex]{Q}_{1} \Rightarrow [/latex] Heat supplied

i.e, [latex]\eta = 1 - \frac{{T}_{1}}{{T}_{2}}[/latex]
15. “ Theoretical limits” for the performance of commonly used engineering systems is determined by

A. Zeroth law of thermodynamics B. First law of thermodynamics C. Second law of thermodynamics D. Third law of thermodynamics

Answer - Option C
Explanation -
Second law of thermodynamics is used in determining the theatrical limits for the the performance of commonly used engineering systems, such as heat engines and refrigerators etc.

1. Radiation of a black body, in terms of its temperature follows:

A. Newton's law of cooling B. Plank's law C. Stefan's law D. Einstein Bose equation

Answer - Option C
2. Consider that two solid bodies A and B are touching each other and transmitting heat through conduction. In the graph below, OX represents the first body and XY represents the second body.

State True (T) or False(F).

1) Temperature gradient is more in A than in B 2) The heat flow is determined by Fourier's law 3) Area under the curve represent s heat dissipation rate.

A. T, T, T B. T, T, F C. T, F, T D. F, F, T

Answer - Option C
3. Stefan Boltzmann Law is applicable for heat Transfer by :

A. Conduction B. Convection C. Radiation D. All of these

Answer - Option C
4. The bending of bimetallic strips during rise in temperature is due to difference in their :

A. Coefficient of linear expansion B. Thickness C. Thermal conductivity D. Elastic properties

Answer - Option A
5. Steady State Heat flow implies

A. negligible flow of heat B. no difference of temperature between the bodies C. constant heat flow rate i.e. heat flow rate independent of time D. uniform rate in temperature rise of a body

Answer - Option C
6. Which of the following fluid flow conditions has high heat transfer coefficient?

A. Free convection in air B. Forced convection in air C. Free convection in water D. Condensation of steam

Answer - Option D
7. The value solar constant is

A. 1353 kW/[latex]{m}^{2}[/latex] B. 1353 W/[latex]{m}^{2}[/latex] C. 1353 J/[latex]{m}^{2}[/latex] D. 135 kJ/[latex]{m}^{2}[/latex]

Answer - Option B
8. "At thermal equilibrium, the ratio of the total emissive power to the total absorptivity is constant for all bodies" is known as

A. Kirchhoff's law B. Wien's displacement law C. Maxwell's theory D. Stefan Boltzmann law

Answer - Option A
9. The substance for which Prandtl number (Pr) [latex]\ll[/latex] 1 is characterized by

A. High rate of heat diffusion B. Low rate of heat diffusion C. High rate of mass diffusion D. Low rate of mass diffusion

Answer - Option A
10. The critical radius of insulation of cylinder is given by

A. k/h B. 2k/h C. k/2h D. k/4h

Answer - Option A
11. 41. Maximum spectral emissive power at temperature (T) is proportional to

A. [latex]{T}^{4}[/latex] B. [latex]{T}^{5}[/latex] C. [latex]{T}^{\frac{5}{2}}[/latex] D. [latex]{T}^{3}[/latex]

Answer - Option B
12. The radiation energy emitted by the Sun between the wavelength of 0.4 [latex]\mu[/latex]n to 0.76 [latex]\mu[/latex]m is known as

A. ultraviolet radiation B. infrared radiation C. thermal radiation D. visible radiation

Answer - Option D
13. To reduce the heat loss with insulation in sphere the following condition should be satisfied

A. [latex]{r}_{insulation thickness} \gg {r}_{critical}[/latex] B. [latex]{r}_{insulation thickness}\ll {r}_{critical}[/latex] C. [latex]{r}_{insulation thickness} = {r}_{critical}[/latex] D. [latex]{r}_{insulation thickness} = 0[/latex]

Answer - Option A
14. The peak frequency at which energy is radiated from a black body radiator is dependent on

A. color B. distance C. intensity D. temperature

Answer - Option D
15. Heat transfer takes place according to

A. Zeroth Law of Thermodynamics B. First Law of Thermodynamics C. Second Law of Thermodynamics D. Third Law of Thermodynamics.

Answer - Option C