MCQOPTIONS
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MCQOPTIONS
This section includes 430 Mcqs, each offering curated multiple-choice questions to sharpen your Thermodynamics knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
In an isothermal expansion of gases |
| A. | Temperature is lowered |
| B. | Temperature shows the extent of expansion |
| C. | Temperature becomes zero |
| D. | Temperature is unaltered |
| E. | Temperature is raised |
| Answer» E. Temperature is raised | |
| 102. |
Brayton cycle cannot be used in reciprocating engines even for same adiabatic compression ratio and work output because |
| A. | Brayton cycle is for slow speed engines |
| B. | Brayton cycle is less efficient |
| C. | Brayton cycle requires large air-fuel ratio |
| D. | Otto cycle is more efficient |
| E. | Large volume of low pressure air cannot be efficiently handled in reciprocating engines |
| Answer» F. | |
| 103. |
Which of the following relations is not valid during throttling process? |
| A. | External work done = Zero |
| B. | Total heat = Constant |
| C. | Pressure drop = Zero |
| D. | Change in enthalpy = Zero |
| E. | Change in internal energy = Zero |
| Answer» D. Change in enthalpy = Zero | |
| 104. |
Which of the following does not change during an-ideal throttling process? |
| A. | Pressure, volume and temperature |
| B. | Enthalpy |
| C. | Pressure and volume |
| D. | Temperature and pressure |
| E. | Enthalpy and temperature |
| Answer» C. Pressure and volume | |
| 105. |
Two ideal engines A and B have their sources at 600 k and 400 k and their sinks at 300 k and 250 k respectively. What inference can be drawn about their efficiency |
| A. | A is more efficient than B |
| B. | A is less efficient than B |
| C. | The information given is incomplete |
| D. | Both are equally efficient |
| E. | Pulsejet |
| Answer» B. A is less efficient than B | |
| 106. |
Highly polished surfaces of a thermosflask prevent heat by |
| A. | Convection |
| B. | Radiation |
| C. | Conduction |
| D. | microns |
| Answer» D. microns | |
| 107. |
Isothermals are curves obtained by drawing |
| A. | P against T |
| B. | P against V |
| C. | V against T |
| D. | PV against T |
| E. | PV against V |
| Answer» C. V against T | |
| 108. |
In case of six stage compression of air for minimum work conditions |
| A. | Pressure rise per stage will be equal |
| B. | Cylinder volumes will be identical |
| C. | Temperature rise in the cylinders will be the same |
| D. | Work done in successive stages will be in geometrical progression |
| E. | Piston diameters will be identical |
| Answer» E. Piston diameters will be identical | |
| 109. |
If the door of a refrigerator in a room is left open, the temperature of the room will |
| A. | decrease |
| B. | Pulsejet |
| C. | remain unaltered |
| D. | increase |
| Answer» F. | |
| 110. |
The value of characteristic gas constant in kg metre per kg per deg C as |
| A. | 29.97 |
| B. | 1554 |
| C. | 848 |
| D. | 96 |
| E. | 53.3 |
| Answer» B. 1554 | |
| 111. |
A carnot cycle engine operating between temperature range of 50?C and 100?C will have the efficiency of nearly |
| A. | 50% |
| B. | 26.80% |
| C. | 13.40% |
| D. | Pulsejet |
| E. | 40% |
| Answer» D. Pulsejet | |
| 112. |
Adiabatic bulk modulus is Y times the isothermal bulk modulus |
| A. | Pulsejet |
| B. | for liquids only |
| C. | for real gases only |
| D. | for perfect gases only |
| E. | for all fluids |
| Answer» F. | |
| 113. |
If the rate of heat flow in aboves case remains constant, the ratio of temperature difference (?t1) (?t2) would be |
| A. | 16 ; 1 |
| B. | 1 ; 4 |
| C. | 8 ; 1 |
| D. | 1 ; 16 |
| E. | 1 ; 8 |
| Answer» B. 1 ; 4 | |
| 114. |
In case of axial flow compressors for minimum fluid driction and blade tip clearance losses, the blades of an axial flow compressor are disigned for |
| A. | 53% reaction |
| B. | 90% reaction |
| C. | 60% reaction |
| D. | Less than 50% reaction |
| E. | 75% reaction |
| Answer» B. 90% reaction | |
| 115. |
The processes or systems that do not involve heat are called |
| A. | Adiabatic processes |
| B. | Steady processes |
| C. | Equilibrium processes |
| D. | Thermal processes |
| E. | Isothermal processes |
| Answer» B. Steady processes | |
| 116. |
If the temperature of the source is increased, the efficiency of the Carnot engine |
| A. | Will be equal to the efficiency of a practical engine |
| B. | Increases |
| C. | Does not change |
| D. | Depends on their factors |
| E. | Decreases |
| Answer» C. Does not change | |
| 117. |
For the same heat inpur and same compression ratio |
| A. | Otto cycle and Diesel cycle are equally efficient |
| B. | Otto cycle is less efficient than diesel cycle |
| C. | Efficiency depends mainly on working substance |
| D. | None of the above |
| E. | Rankine |
| Answer» E. Rankine | |
| 118. |
Which two cycles have one constant volume, one constant pressure and two adiabatic processes each? |
| A. | Brayton and Joules cycle |
| B. | Diesel and Dual cycles |
| C. | Otto and Carnot cycles |
| D. | Sterling and Diesel cycles |
| E. | Pulsejet |
| Answer» E. Pulsejet | |
| 119. |
For water which of the following will be reduced to zero at critical pressure? |
| A. | Specific volume |
| B. | Enthalpy |
| C. | Internal energy |
| D. | Latent heat of vaporisation |
| E. | None of the above |
| Answer» E. None of the above | |
| 120. |
A fusible plug is utilised when |
| A. | Impurities in water are excessive |
| B. | Water level is too low |
| C. | Water level is too high |
| D. | Firing rate is high |
| E. | Steam generation rate is high |
| Answer» C. Water level is too high | |
| 121. |
The ratio of heat flow QA/QB from two walls of same thickness having thermal conductivity kA = 2 kB, for the same temperature difference will be |
| A. | 1 |
| B. | 2 |
| C. | 0.5 |
| D. | None of the above |
| Answer» D. None of the above | |
| 122. |
The vapour pressure of water at 30?C in pascals is |
| A. | 0.44 |
| B. | 4315 |
| C. | 223 |
| D. | 431.5 |
| E. | 7.18 |
| Answer» C. 223 | |
| 123. |
In case of centrifugal compressors, the phenomenon of air stream not able to follow the blade contour of an axial compressor is known as |
| A. | Stalling |
| B. | Feedback |
| C. | Regeneration |
| D. | Recirculation |
| E. | Surging |
| Answer» B. Feedback | |
| 124. |
In Porous plug experiment the change in temperature of a gas depends upon |
| A. | its molecular weight |
| B. | its specific heat |
| C. | pressure gradient on either side |
| D. | All of the above |
| E. | Pulsejet |
| Answer» D. All of the above | |
| 125. |
Of the following first law statements, choose the one that is wrong |
| A. | the net heat transfer equals the network for a cycle |
| B. | the heat transfer equals the work plus the energy change |
| C. | the heat transfer cannot exceed the work done |
| D. | Pulsejet |
| E. | the energy of an isolated system remains constant |
| Answer» D. Pulsejet | |
| 126. |
In an adiabatic change the system |
| A. | Heat taken from surroundings is exactly equal to heat rejected to surroundings |
| B. | Exchanges no heat with the surroundings |
| C. | Gives heat to the surrounding |
| D. | Partly takes heat and partly leaves to the surroundings |
| E. | Takes heat from the surroundings |
| Answer» C. Gives heat to the surrounding | |
| 127. |
Triple point |
| A. | Occurs in sublimation |
| B. | Occurs in a mixture of two or more gases |
| C. | Is the range of temperature within which three constituents simultaneously change phase |
| D. | Is that point where three phases solid, liquid and gas exist together |
| E. | None of the above |
| Answer» E. None of the above | |
| 128. |
An ordinary mercury thermometer can be used for temperatures about |
| A. | 200?C |
| B. | 400?C |
| C. | 300?C |
| D. | 100?C |
| E. | 500?C |
| Answer» D. 100?C | |
| 129. |
If all the variables of a steam are in-dependent of time it is said to be in |
| A. | Unsteady flow |
| B. | Uniform flow |
| C. | Steady flow |
| D. | Closed flow |
| E. | Constant flow |
| Answer» D. Closed flow | |
| 130. |
Which of the following is a path function quantity? |
| A. | Work done |
| B. | Pressure |
| C. | Pulsejet |
| D. | Temperature |
| E. | Enthalpy |
| Answer» B. Pressure | |
| 131. |
A system comprising a single phase is called a |
| A. | Open system |
| B. | Isolated system |
| C. | Closed system |
| D. | Homogeneous system |
| E. | Heterogeneous system |
| Answer» E. Heterogeneous system | |
| 132. |
Entropy of mixing is always |
| A. | positive |
| B. | Zero |
| C. | Negative |
| D. | Pulsejet |
| Answer» B. Zero | |
| 133. |
The weight of 1 cu-m of carbon dioxide at NTP if the characteristic gas constant is 19.28 kg metre/kg/?C, would be |
| A. | 3.924 kg |
| B. | 2.5 kg |
| C. | 1.962 kg |
| D. | 1 kg |
| E. | 1.5 kg |
| Answer» D. 1 kg | |
| 134. |
In the regenerative cycle |
| A. | Power is generated in two stages |
| B. | Part of the steam is withdrawn from the turbine and is utilised in heating the exhaust steam |
| C. | Steam is reheated after expansion and again used |
| D. | Part of the steam is withdrawn from the turbine and is used in heating the steam being supplied to the turbine |
| E. | Part of the steam is withdrawn from the turbine and is used in heating the feed water |
| Answer» F. | |
| 135. |
Carburetted water gas is obtained by |
| A. | heating water at high temperature in a copper vessel |
| B. | Burning oil |
| C. | spraying oil into a carburettor filled with hot brick elieckar work through which the gases pass |
| D. | Pulsejet |
| E. | Passing alternately steam and air through while hot carbon |
| Answer» F. | |
| 136. |
The ability of gasoline to resist detonation during combustion is given by |
| A. | iso-octane number |
| B. | heptane number |
| C. | Pulsejet |
| D. | Cetane number |
| E. | Octane number |
| Answer» F. | |
| 137. |
The gas turbine works on |
| A. | Rankine cycle |
| B. | Brayton cycle |
| C. | Erricson cycle |
| D. | Otto cycle |
| E. | Carnot cycle |
| Answer» C. Erricson cycle | |
| 138. |
Which of the following is not a characteristic of liquid air? |
| A. | It will cause rubber to become brittle |
| B. | Pulsejet |
| C. | It will freeze mercury and ammonia |
| D. | It has no surface tension |
| E. | It will separate out lead from solder |
| Answer» D. It has no surface tension | |
| 139. |
Otto cycle consists of the set of processes as |
| A. | Two isentropics and two constant volumes |
| B. | Two isothermal and two constant volume |
| C. | Two isentropics and two constant pressure |
| D. | Two adiabatic and two isothermal |
| E. | Two isothermal and two constant pressure |
| Answer» B. Two isothermal and two constant volume | |
| 140. |
Which of the following changes during throttling process? |
| A. | Pressure |
| B. | Temperature |
| C. | Internal energy |
| D. | Pressure x Volume |
| E. | All of the above |
| Answer» B. Temperature | |
| 141. |
In a steam turbine when steam expands, the entropy |
| A. | Decreases exponentially |
| B. | Does not change |
| C. | Increases exponentially |
| D. | Decreases linearly |
| E. | Increases linearly |
| Answer» C. Increases exponentially | |
| 142. |
Which of the following relation does not hold good for a throttling process? |
| A. | dQ = 0 |
| B. | dS = 0 |
| C. | Pulsejet |
| D. | dH = 0 |
| E. | dW = 0 |
| Answer» C. Pulsejet | |
| 143. |
In a Joule cycle, the heat is rejected at |
| A. | Constant pressure |
| B. | Constant enthalpy |
| C. | Constant temperature |
| D. | Constant volume |
| E. | Constant entropy |
| Answer» B. Constant enthalpy | |
| 144. |
"The molecular weights of all the perfect gases occupy the same volume under same conditions of pressure and temperature". |
| A. | Boyle's law |
| B. | Regnault's law |
| C. | Avogadro's hypothesis |
| D. | Balton's law |
| E. | Gay Lussac's law |
| Answer» D. Balton's law | |
| 145. |
The specific heat of water |
| A. | Decreases with rise of temperature |
| B. | First increases, reaches a maximum value and then decreases. |
| C. | Increases with rise of temperature |
| D. | First decreases, reaches a minimum value and then increases |
| E. | Does not change with temperature |
| Answer» E. Does not change with temperature | |
| 146. |
The first law of thermodynamics, for steady flow |
| A. | Accounts for all energy entering and leaving a control volume |
| B. | Is primarily concerned with heat transfer |
| C. | Is restricted in its application to perfect gases |
| D. | Is an energy balance for the specified mass of fluid |
| E. | Is an expression of the conservation of linear momentum |
| Answer» B. Is primarily concerned with heat transfer | |
| 147. |
Five people must be lifted in an elevator to a distance of 100 m. The work is found to be 341.2 kJ and the gravitational acceleration is 9.75 m/s2. The average mass per person is |
| A. | Pulsejet |
| B. | 72 kg |
| C. | 70 kg |
| D. | 67.5 kg |
| E. | 65 kg |
| Answer» D. 67.5 kg | |
| 148. |
Ericsson cycle processes are |
| A. | Two adiabatic, constant volume and constant pressure |
| B. | Two isothermals and two constant pressures |
| C. | Two isothermals and two isentropics |
| D. | Two isothermals and two constant volumes |
| E. | Two isothermals and two isentropics |
| Answer» C. Two isothermals and two isentropics | |
| 149. |
The number of degrees of freedom in case of diatomic gases is |
| A. | 2 |
| B. | 3 |
| C. | 5 |
| D. | 6 |
| E. | 4 |
| Answer» D. 6 | |
| 150. |
287 J/kg/?k is the value of |
| A. | Gas constant in MKS units |
| B. | Gas constant in S.I. units |
| C. | Universal gas constant in MKS units |
| D. | Universal gas constant in S.I. units |
| E. | None of the above |
| Answer» C. Universal gas constant in MKS units | |