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MCQOPTIONS
This section includes 2670 Mcqs, each offering curated multiple-choice questions to sharpen your Railways knowledge and support exam preparation. Choose a topic below to get started.
| 2151. |
Zeroth law of thermodynamics deals with: |
| A. | concept of temperature |
| B. | enthalpy |
| C. | entropy |
| D. | external and internal energy both |
| Answer» B. enthalpy | |
| 2152. |
What are the limitations to the signs of heat exchange from hot cold reservoirs if a two-temperature machine operates between two Positive temperatures |
| A. | heat must be rejected to hot source and abstracted from cold source |
| B. | heat must be abstracted from hot source and rejected to cold source |
| C. | heat must be rejected to both the sources |
| D. | heat must be abstracted from both the sources |
| Answer» C. heat must be rejected to both the sources | |
| 2153. |
The ideal efficiency of a Stirling cycle with perfect regeneration and operating between two given temperature limits is |
| A. | equal to Carnot cycle |
| B. | less than Carnot cycle |
| C. | equal to Brayton cycle |
| D. | equal to Joule cycle |
| Answer» B. less than Carnot cycle | |
| 2154. |
Otto cycle consists of following four processes |
| A. | two isothermals and two isentropics |
| B. | two isentropics and two constant volumes |
| C. | two insentropics and one constant volume and one constant pressure |
| D. | Two isentropics and two constant pressures |
| Answer» C. two insentropics and one constant volume and one constant pressure | |
| 2155. |
What are the properties of a thermodynamic system, whose value for the entire system is equal to the sum of their values for individual parts of the system? |
| A. | Thermodynamic properties |
| B. | Extensive properties |
| C. | Intensive properties |
| D. | None of the above |
| Answer» D. None of the above | |
| 2156. |
When a convergent-divergent nozzle is subjected to a pressure ratio \[{{{p}_{2}}}/{{{p}_{1}}}\;\] greater than the critical pressure ratio, what does the divergent section exhibit? |
| A. | Decreasing pressure |
| B. | Flow separation |
| C. | Normal shock |
| D. | Increasing pressure |
| Answer» B. Flow separation | |
| 2157. |
What does choked flow through a steam nozzle mean? 1. Discharge is maximum 2. Discharge is zero 3. Throat velocity is sonic 4. Exit pressure is less than or equal to critical pressure Select the correct answer using the code given below: |
| A. | 1 only |
| B. | 2 only |
| C. | 1 and 3 only |
| D. | 1, 3 and 4 |
| Answer» D. 1, 3 and 4 | |
| 2158. |
A system of 100 kg mass undergoes a process in which its specific entropy increase's from 0.30 kJ/kg K to 0.35 kJ/kg K. At the same time, the entropy of the surroundings decreases from 80 kJ/K to 75 kJ/K. What is the type of this process? |
| A. | Reversible |
| B. | Irreversible |
| C. | Impossible |
| D. | Not identifiable with the data given |
| Answer» B. Irreversible | |
| 2159. |
A 100Q resistor carrying a constant current of 0.5 A is kept at a constant temperature of 300 K by a stream of cooling water. In a time interval of 30 minutes, what are the changes in entropy for the resistor and that of the universe, respectively? |
| A. | 0 and 150 J/K |
| B. | 150 J/K and 0 |
| C. | 300 J/K and 0 |
| D. | 0 and 300 J/K |
| Answer» B. 150 J/K and 0 | |
| 2160. |
A reversible engine exchanges heat from three thermal reservoirs A, B and C at 1000 K, 800 K and 200 K respectively. If the engine receives 500 kJ from .A and 400 kJ from B, then what is the heat exchanged from thermal reservoir C? |
| A. | 450 kJ rejected to thermal reservoir C |
| B. | 350 kJ rejected to thermal reservoir C |
| C. | 250 kJ rejected to thermal reservoir C |
| D. | 200 kJ rejected to thermal reservoir C |
| Answer» E. | |
| 2161. |
A refrigerating machine working on reversed Carnot cycle takes out 2 kW of heal from the system at 200 K while working between temperature limits of 300 K and 200 K. COP and power consumed by the cycle will respectively, be: |
| A. | 1 and 1 kW |
| B. | 1 and 2 kW |
| C. | 2 and 1 kW |
| D. | 2 and 2 kW |
| Answer» D. 2 and 2 kW | |
| 2162. |
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 the mass transfer is controlled by valves |
| Answer» C. There is no energy transfer. But mass transfer exists | |
| 2163. |
Match List-I with List-II and select the correct answer using the codes given below the lists: List-I List-II A. Reversible cycle 1. Measurement of temperature B. Mechanical work 2. Clapeyron equation C. Zeroth Law 3. Clausius Theorem D. Heat 4. High grade energy 5. \[{{3}^{rd}}\] Law of thermodynamics 6. In exact differential Codes: |
| A. | A\[\to \]3, B\[\to \]4, C\[\to \]1, D\[\to \]6 |
| B. | A\[\to \]2, B\[\to \]6, C\[\to \]1, D\[\to \]3 |
| C. | A\[\to \]3, B\[\to \]1, C\[\to \]5, D\[\to \]6 |
| D. | A\[\to \]1, B\[\to \]4, C\[\to \]5, D\[\to \]2 |
| Answer» C. A\[\to \]3, B\[\to \]1, C\[\to \]5, D\[\to \]6 | |
| 2164. |
In an adiabatic process 6000 J of work is performed on a system. In the non-adiabatic process by which the system returns to its original state, 1000 J of heat is added to the system. What is the work done during non-adiabatic process? |
| A. | \[+\,\,7000\,\,J\] |
| B. | \[-\,\,7000\,\,J\] |
| C. | \[+\,\,5000\,\,J\] |
| D. | \[-\,\,5000\,\,J\] |
| Answer» B. \[-\,\,7000\,\,J\] | |
| 2165. |
Total enthalpy of steam at the inlet of a nozzle is 2800 kJ while static enthalpy at the exit is 2555 kJ. What is the steam velocity at the exit if expansion is isentropic? |
| A. | 70 m/s |
| B. | 245 m/s |
| C. | 450 m/s |
| D. | 700 m/s |
| Answer» E. | |
| 2166. |
A higher value of Van der Waals constant for a gas indicates that the: |
| A. | Molecules of the gas have smaller diameter |
| B. | Gas can be easily liquified |
| C. | Gas has higher molecular weight |
| D. | Gas has lower molecular weight |
| Answer» E. | |
| 2167. |
In a normal shock wave in one-dimensional flow: |
| A. | Pressure, density and temperature increase |
| B. | Velocity, temperature and density increase |
| C. | Pressure, density and temperature decrease |
| D. | Velocity, pressure and density decrease |
| Answer» B. Velocity, temperature and density increase | |
| 2168. |
An inventor claims that heat engine has the following specifications: Power developed = 50 kW, Fuel burned per hour = 3 kg Heating value of fuel = 75,000 kJ per kg Temperature limits = \[627{}^\circ C\] and \[27{}^\circ C\] Cost of fuel =Rs. 30/kg. Value of power = Rs. 5/kWh, The performance of his engine is: |
| A. | Possible |
| B. | not possible |
| C. | Economical |
| D. | uneconomical |
| Answer» C. Economical | |
| 2169. |
Match List-I with List-II and select the correct answer using the codes given below the lists: List-I List-II A. Joule-Thomson coefficient 1. 5/2 R B. \[{{c}_{p}}\] for monoatomic gas 2. \[{{c}_{v}}\] C. \[{{c}_{p}}-{{c}_{v}}\] for diatomic gas 3. R D. \[{{\left( \frac{\partial U}{\partial T} \right)}_{v}}\] 4. \[{{\left( \frac{\partial T}{\partial p} \right)}_{h}}\] Codes: |
| A. | A\[\to \]3, B\[\to \]2, C\[\to \]4, D\[\to \]1 |
| B. | A\[\to \]4, B\[\to \]1, C\[\to \]3, D\[\to \]2 |
| C. | A\[\to \]3, B\[\to \]1, C\[\to \]4, D\[\to \]2 |
| D. | A\[\to \]4, B\[\to \]2, C\[\to \]3, D\[\to \]1 |
| Answer» C. A\[\to \]3, B\[\to \]1, C\[\to \]4, D\[\to \]2 | |
| 2170. |
Match List-I (Quantity) with List-II (Measuring Device) and select the correct answer using the codes given below the lists: List-I (Quantity) List-II (Measuring Device) A. Engine speed 1. Manometer B. Fuel heating value 2. Tachometer C. Air velocity 3. Hydrometer D. Relative humidity of air 4. Calorimeter 5. Hygrometer Codes: |
| A. | A\[\to \]2, B\[\to \]5, C\[\to \]1, D\[\to \]4 |
| B. | A\[\to \]1, B\[\to \]5, C\[\to \]3, D\[\to \]4 |
| C. | A\[\to \]2, B\[\to \]4, C\[\to \]1, D\[\to \]5 |
| D. | A\[\to \]1, B\[\to \]4, C\[\to \]3, D\[\to \]5 |
| Answer» D. A\[\to \]1, B\[\to \]4, C\[\to \]3, D\[\to \]5 | |
| 2171. |
Work done in a free expansion process is: |
| A. | Positive |
| B. | negative |
| C. | Zero |
| D. | maximum |
| Answer» D. maximum | |
| 2172. |
In isentropic flow between two points: |
| A. | The stagnation pressure decreases in the direction of flow |
| B. | The stagnation temperature and stagnation pressure decrease with increase in the velocity |
| C. | The stagnation temperature and stagnation pressure may vary |
| D. | The stagnation temperature and stagnation pressure remain constant |
| Answer» D. The stagnation temperature and stagnation pressure remain constant | |
| 2173. |
A heat engine working on Carnot cycle receives heat at the rate of 40 kW from a source at 1200 K and rejects it to a sink at 300 K. The heat rejected is: |
| A. | 30 kW |
| B. | 20 kW |
| C. | 10 kW |
| D. | 5 kW |
| Answer» D. 5 kW | |
| 2174. |
Clausius inequality is stated as: |
| A. | \[\oint{\delta Q<0}\] |
| B. | \[\oint{\delta Q\,\,=\,\,0}\] |
| C. | \[\oint{\frac{\delta Q}{T}>0}\] |
| D. | \[\oint{\frac{\delta Q}{T}\le 0}\] |
| Answer» E. | |
| 2175. |
Which of the following statements are associated with second law of thermodynamics 1. When a system executes a cyclic process, network transfer is equal to net heat transfer. 2. It is impossible to construct an engine, that operating in a cycle will produce no other effect than the extraction of heat from a reservoir and performance of an equivalent amount of work. 3. It is impossible by any procedure, no matter how idealized, to reduce any system the absolute zero of temperature in a finite number of operations 4. It is impossible to construct a device that operating in a cycle will produce no effect other than transfer of heat from a cooler to hotter body. Select the correct answer using the codes given below: |
| A. | 1, 2 and 4 |
| B. | 2 and 4 |
| C. | 2, 3 and 4 |
| D. | 2 and 3 |
| Answer» D. 2 and 3 | |
| 2176. |
Constant pressure lines in the superheated region of the Mother diagram have what type of slope? |
| A. | A positive slope |
| B. | A negative slope |
| C. | Zero slope |
| D. | May have either positive or negative slope. |
| Answer» B. A negative slope | |
| 2177. |
Consider the following statements: 1. Two reversible adiabatics can never intersect each other. 2. for a thermodynamic process \[\frac{dQ}{T}+1\ge 0,\] where I is the measure of irreversibility. Which of the statements given above is/are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | Both 1 and 2 |
| D. | neither 1 nor 2 |
| Answer» B. 2 only | |
| 2178. |
Which one of the following relationships defines Gibbs' free energy G? |
| A. | \[G=H+TS\] |
| B. | \[G=H-TS\] |
| C. | \[G=U+7S\] |
| D. | \[G=U-TS\] |
| Answer» C. \[G=U+7S\] | |
| 2179. |
1600 kJ of energy is transferred from a heat reservoir at 800 K. to another heat reservoir at 400 K. The amount of entropy generated during the process would be: |
| A. | 6 kJ/K |
| B. | 4 kJ/K |
| C. | 2 kJ/K |
| D. | zero. |
| Answer» D. zero. | |
| 2180. |
Match List-I with List-II and select the correct answer using the codes given below the lists: List-I List-II A. The entropy of a pure crystalline substance is zero at absolute zero temperature 1. First law of thermodynamics B. Spontaneous processes occur in a certain direction 2. Second law of thermodynamics C. If two bodies are in thermal equilibrium with a third body, then they are also in thermal equilibrium with each other 3. Third law of thermodynamics D. The law of conservation of energy 4. Zeroth law of thermodynamics Codes: |
| A. | A\[\to \]2, B\[\to \]3, C\[\to \]4, D\[\to \]1 |
| B. | A\[\to \]3, B\[\to \]2, C\[\to \]1, D\[\to \]4 |
| C. | A\[\to \]3, B\[\to \]2, C\[\to \]4, D\[\to \]1 |
| D. | A\[\to \]2, B\[\to \]3, C\[\to \]1, D\[\to \]4 |
| Answer» D. A\[\to \]2, B\[\to \]3, C\[\to \]1, D\[\to \]4 | |
| 2181. |
In a test of a water-jacketed compressor, the shaft work required is 90 kN\[\,-\,\]m/kg of air compressed. During compression, increase in enthalpy of air is 30 kJ/kg of air and increase in enthalpy of circulating cooling water is 40 kJ/kg of air. The change in velocity is negligible. The amount of heat lost to the atmosphere from the compressor per kg of air is: |
| A. | 20 kJ |
| B. | 60 kJ |
| C. | 80 kJ |
| D. | 120 kJ |
| Answer» E. | |
| 2182. |
Air is compressed adiabatically in a steady flow process with negligible change in potential and kinetic energy. The work done in the process is given by: |
| A. | \[-\,\int{p\,\,dv}\] |
| B. | \[+\,\int{p\,\,dv}\] |
| C. | \[-\,\int{v\,\,dp}\] |
| D. | \[+\,\int{v\,\,dp}\] |
| Answer» D. \[+\,\int{v\,\,dp}\] | |
| 2183. |
A section diverging in the direction of flow can be used as which of the following? 1. Subsonic nozzle 2. Supersonic nozzle 3. Subsonic diffuser 4. Supersonic diffuser Select the correct answer using the code given below: |
| A. | 1 only |
| B. | 2 and 3 |
| C. | 1 and 4 |
| D. | 3 only |
| Answer» C. 1 and 4 | |
| 2184. |
The air standard efficiency of Diesel cycle will be less than that of Otto cycle in the case of: |
| A. | Same compression ratio and same heat input |
| B. | Same maximum pressure and same heat input |
| C. | Same maximum pressure and same output |
| D. | Same maximum pressure and same maximum temperature |
| Answer» B. Same maximum pressure and same heat input | |
| 2185. |
If a system undergoes an irreversible adiabatic process, then (symbols have usual meanings: |
| A. | \[\int{\frac{dQ}{T}}\,\,=\,\,0\] and \[\Delta \,S>0\] |
| B. | \[\int{\frac{dQ}{T}\,\,=\,\,0}\] and \[\Delta \,S\,\,=\,\,0\] |
| C. | \[\int{\frac{dQ}{T}>0}\] and \[\Delta \,S\,\,=\,\,0\] |
| D. | \[\int{\frac{dQ}{T}<0}\] and \[\Delta \,S<0\] |
| Answer» E. | |
| 2186. |
The heat transferred in a thermodynamic cycle of a system consisting of four processes are successively 0, 8, 6 and \[-\,\,4\] units. The net change in the internal energy of the system will be: |
| A. | \[-\,\,8\] |
| B. | zero |
| C. | 10 |
| D. | \[-\,\,10\] |
| Answer» D. \[-\,\,10\] | |
| 2187. |
For a Carnot engine \[{{T}_{1}}>{{T}_{2}}.\] When \[{{T}_{2}}\] is decreased by \[\Delta T\] with \[{{T}_{1}}\] remaining same then efficiency is \[{{\eta }_{1}},\] and when \[{{T}_{1}}\] is increased by \[\Delta T\] with \[{{T}_{2}}\] remaining same, efficiency is \[{{\eta }_{2}}.\] Which one of the following is the correct expression for \[\left( {{\eta }_{1}}-{{\eta }_{2}} \right)?\] |
| A. | \[\frac{({{T}_{2}}-{{T}_{1}})\,\,\Delta \,T+{{(\Delta \,T)}^{2}}}{{{T}_{2}}({{T}_{2}}+\Delta \,T)}\] |
| B. | \[\frac{({{T}_{2}}-{{T}_{1}})\,\,\Delta \,T+{{(\Delta \,T)}^{2}}}{{{T}_{1}}({{T}_{1}}+\Delta \,T)}\] |
| C. | \[\frac{({{T}_{1}}-{{T}_{2}})\,\,\Delta \,T+{{(\Delta \,T)}^{2}}}{{{T}_{1}}({{T}_{1}}+\Delta \,T)}\] |
| D. | \[\frac{({{T}_{1}}-{{T}_{2}})\,\,\Delta \,T+{{(\Delta T)}^{2}}}{{{T}_{1}}({{T}_{1}}+\Delta T)}\] |
| Answer» D. \[\frac{({{T}_{1}}-{{T}_{2}})\,\,\Delta \,T+{{(\Delta T)}^{2}}}{{{T}_{1}}({{T}_{1}}+\Delta T)}\] | |
| 2188. |
Which one of the following cycles working within the same temperature limits has the highest work ratio? |
| A. | Carnot cycle |
| B. | Joule cycle |
| C. | Otto cycle |
| D. | Rankine cycle. |
| Answer» B. Joule cycle | |
| 2189. |
For air standard Brayton cycle, increase in the maximum temperature of the cycle, while keeping the pressure ratio the same, would result in: |
| A. | Increase in air standard efficiency |
| B. | Decrease in air standard efficiency |
| C. | No change in air standard efficiency |
| D. | Increase in the efficiency but reduction in network |
| Answer» D. Increase in the efficiency but reduction in network | |
| 2190. |
Match List-I with List-II and select the correct answer using the codes given below the lists: List-I List-II A. Irreversibility 1. Mechanical equivalent B. Joule-Thomson experiment 2. Thermodynamic temperature scale C. Joule?s experiment 3. Throttling process D. Reversible engine 4. Loss of availability Codes: |
| A. | A\[\to \]1, B\[\to \]2, C\[\to \]3, D\[\to \]4 |
| B. | A\[\to \]1, B\[\to \]2, C\[\to \]4, D\[\to \]3 |
| C. | A\[\to \]4, B\[\to \]3, C\[\to \]2, D\[\to \]1 |
| D. | A\[\to \]4, B\[\to \]3, C\[\to \]1, D\[\to \]2 |
| Answer» E. | |
| 2191. |
Which one of the following is the correct expression for change in the internal energy for a small temperature change \[\Delta T\] for an ideal gas? |
| A. | \[\Delta u={{c}_{v}}\times \Delta T\] |
| B. | \[\Delta u={{c}_{p}}\times \Delta T\] |
| C. | \[\Delta u=\frac{{{c}_{p}}}{{{c}_{v}}}\times \Delta T\] |
| D. | \[\Delta u=\left( {{c}_{p}}-{{c}_{v}} \right)\Delta T\] |
| Answer» B. \[\Delta u={{c}_{p}}\times \Delta T\] | |
| 2192. |
Which of the following are pure substances? 1. Steam and water mixture in a container 2. Atmospheric air 3. Air and liquid air in a container 4. Gaseous combustion products Select the correct answer using the codes given below: Codes: |
| A. | 1, 2 and 3 and 4 |
| B. | 2, 3 and 4 |
| C. | 1, 3 and 4 |
| D. | 1, 2 and 4 |
| Answer» B. 2, 3 and 4 | |
| 2193. |
If a pure substance contained in a rigid vessel passes through the critical state on heating, its initial state should be: |
| A. | Sub cooled water |
| B. | Saturated water |
| C. | Wet steam |
| D. | Saturated steam |
| Answer» E. | |
| 2194. |
Which one of the following expressions for Tds is true for a simple compressible substance? (Notations have the usual meaning) |
| A. | \[dh-vdp\] |
| B. | \[dh+vdp\] |
| C. | \[dh-pdv\] |
| D. | \[dh+pdv\] |
| Answer» B. \[dh+vdp\] | |
| 2195. |
A reversible heat engine operating between hot and cold reservoirs delivers a work output of 54 kJ white it rejects a heat of 66 kJ. The efficiency of this engine |
| A. | 0.45 |
| B. | 0.66 |
| C. | 0.75 |
| D. | 0.82 |
| Answer» B. 0.66 | |
| 2196. |
Thermodynamic work is the product of: |
| A. | Two intensive properties |
| B. | Two extensive properties |
| C. | An intensive property and change in an extensive property |
| D. | An extensive property and change in an intensive property |
| Answer» D. An extensive property and change in an intensive property | |
| 2197. |
A heat engine in a thermodynamic cycle draws 500 kJ of heat energy from a source at 1000 K per cycle and rejects certain amount of heat energy at 300 K per cycle. Then, which one of the following is correct? |
| A. | The amount of heat energy rejected must be 150 kJ |
| B. | The amount of heat energy rejected must be less than 150 kJ |
| C. | (e) The amount of heat energy rejected must be greater than 150 kJ |
| D. | It is not possible to make any statement regarding the amount of heat energy rejected per cycle from the data given |
| Answer» B. The amount of heat energy rejected must be less than 150 kJ | |
| 2198. |
A closed system undergoes a process during which 150 kJ of heat is added to it. The system is then restored to its initial state. If the heat transfer and work transfer for the second process are \[-\,\,50\,\,kJ\] and \[+\,\,75\,\,kJ\] respectively, what is the work transfer for the first process? |
| A. | 25 kJ |
| B. | 50 kJ |
| C. | 75 kJ |
| D. | 100 kJ |
| Answer» E. | |
| 2199. |
Which thermometer is independent of the substance or material used in its construction? |
| A. | Mercury thermometer |
| B. | Alcohol thermometer |
| C. | Ideal gas thermometer |
| D. | Resistance thermometer |
| Answer» D. Resistance thermometer | |
| 2200. |
During a cycle comprising four processes, the heat transfers during three processes are \[+\,\,45\,\,kJ,\] \[-\,\,30\,\,kJ,\] \[-\,\,25\,\,kJ.\] what should be the heat transfer during the fourth process so that the network done during the cycle is zero? |
| A. | Zero |
| B. | \[+\,\,10\,\,kJ\] |
| C. | \[-\,\,10\,\,kJ\] |
| D. | \[-\,\,20\,\,kJ\] |
| Answer» C. \[-\,\,10\,\,kJ\] | |