McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 151. |
The statement that the entropy of a pure substance in complete theromodynamic equilibrium becomes zero at the absolute zero of temperature is known as |
| A. | First law of thermodynamics |
| B. | Third law of thermodynamics |
| C. | Law of entropy |
| D. | Zeroth law of thermodynamics |
| E. | Second law of thermodynamics |
| Answer» B. Third law of thermodynamics | |
| 152. |
A Carnot refrigerator extracts 100 kcal of heat per minute from a cold room which is maintained at - 15?C and it is discharged to atmosphere at 30?C. The horse power required to run the unit would be |
| A. | 1 |
| B. | 1.5 to 2 |
| C. | Mone than 6 |
| D. | 2 to 5 |
| E. | 5 to 6 |
| Answer» B. 1.5 to 2 | |
| 153. |
The function of a distributor is |
| A. | To distribute fuel |
| B. | To distribute spark |
| C. | To time the spark |
| D. | To distribute power |
| E. | To generate the spark |
| Answer» C. To time the spark | |
| 154. |
A petrol engine fuel that knocks at a low speed |
| A. | Pulsejet |
| B. | will have low fire point |
| C. | has a high octane rating |
| D. | will always knock at high speed |
| E. | may not knock at high speed |
| Answer» D. will always knock at high speed | |
| 155. |
Which of the following does not use ambient air for propulsion? |
| A. | Rocket |
| B. | Turboprop |
| C. | Turbojet |
| D. | Pulsojet |
| E. | Propellor |
| Answer» A. Rocket | |
| 156. |
During constant pressure heating of a gas the following does not increase? |
| A. | Pressure |
| B. | Pulsejet |
| C. | Volume |
| D. | Entropy |
| E. | Temperature |
| Answer» A. Pressure | |
| 157. |
A safety valve is used on boilers to |
| A. | Check the level of water |
| B. | Check the level of steam |
| C. | Check the temperature of steam |
| D. | To release excess pressure |
| E. | None of the above |
| Answer» D. To release excess pressure | |
| 158. |
For an ideal gas the value of Joule Kelvin coefficient is |
| A. | Negative |
| B. | Unity |
| C. | Infinite |
| D. | Zero |
| E. | 0.5 |
| Answer» D. Zero | |
| 159. |
Which of the following cycle consists of two isothemal and two constant volume processes? |
| A. | Joule cycle |
| B. | Stirling cycle |
| C. | Diesel cycle |
| D. | Rankine cycle |
| E. | Otto cycle |
| Answer» B. Stirling cycle | |
| 160. |
The statement that energy can be neigher created nor destroyed but only converted from one form to another, is known as |
| A. | Zerothlaw of thermodynamics |
| B. | Second law of thermodynamics |
| C. | First law of theormodynamics |
| D. | Avogadro's hypothesis |
| E. | Kinetic theory of gases |
| Answer» C. First law of theormodynamics | |
| 161. |
Avogadro's numbers is |
| A. | 60248.6 x 1026 molecules/(k mol) |
| B. | 6024.86 x 1026 molecules/(k mol) |
| C. | 6.02486 x 1026 molecules/(k mol) |
| D. | 60.2486 x 1026 molecules/(k mol) |
| E. | 602.486 x 1026 molecules/(k mol) |
| Answer» C. 6.02486 x 1026 molecules/(k mol) | |
| 162. |
The triple point of a substance is the temperature and pressure at which |
| A. | The solid and liquid phases are in equilibrium |
| B. | The liquid and gaseous phases are in equilibrium |
| C. | The solid, liquid and the gaseous phases are in equilibrium |
| D. | The solid does not melt, the liquid does not boil and the gas does not condense |
| E. | Temperature shows the extent of expansion |
| Answer» C. The solid, liquid and the gaseous phases are in equilibrium | |
| 163. |
During the boiling of a liquid, which of the following parameter increases? |
| A. | Temperature |
| B. | Free energy |
| C. | Entropy |
| D. | Heat of vaporisation |
| E. | None of the above |
| Answer» C. Entropy | |
| 164. |
Economiser in the boiler heats the |
| A. | Steam |
| B. | Air |
| C. | Feed water |
| D. | Coal |
| E. | None of the above |
| Answer» C. Feed water | |
| 165. |
For a closed system, the difference between the heat added to the system and the work done by the system is equal to the change in |
| A. | entropy |
| B. | enthalpy |
| C. | internal energy |
| D. | Pulsejet |
| E. | temperature |
| Answer» C. internal energy | |
| 166. |
The area inside the PV diagram for a diesel engine represents |
| A. | heat supplied |
| B. | work done |
| C. | work supplied |
| D. | Pulsejet |
| E. | change in entropy |
| Answer» B. work done | |
| 167. |
In case of ideal monoatomic gas, the ratio of specific heats Cp/Cv would be |
| A. | 1 |
| B. | 1.67 |
| C. | 1.41 |
| D. | 1.4 |
| E. | 1.33 |
| Answer» B. 1.67 | |
| 168. |
Least value of specific heat |
| A. | Water |
| B. | Ice |
| C. | Alcohol |
| D. | Air |
| E. | Stream |
| Answer» D. Air | |
| 169. |
Triple point temperature and pressure for water are |
| A. | 0.1?C and 0.006028 ata |
| B. | 100?C and 1 ata |
| C. | 0.01?C and 0.006028 ata |
| D. | 0?C and 0.1 ata |
| E. | 0?C 1 ata |
| Answer» C. 0.01?C and 0.006028 ata | |
| 170. |
The shape of the lid of manhole in a boiler is |
| A. | Circular |
| B. | Elliptical |
| C. | Rectangular |
| D. | Square |
| E. | Special contour |
| Answer» B. Elliptical | |
| 171. |
The process in which the change in internal energy of a gas is equal to the work done is known as |
| A. | adiabatic process |
| B. | isochoric process |
| C. | isobaric process |
| D. | isothermal process |
| E. | Pulsejet |
| Answer» A. adiabatic process | |
| 172. |
During an adiabatic expansion the increase in volume is associated with |
| A. | Decrease in pressure and decrease in temperature |
| B. | Increase in pressure and decrease in temperature |
| C. | Depends on other factors |
| D. | Increase in pressure and increase in temperature |
| E. | Decrease in pressure and increase in temperature |
| Answer» A. Decrease in pressure and decrease in temperature | |
| 173. |
In six stage compression of air set for minimum work conditions |
| A. | Pressure rise per stage will be equal |
| B. | Cylinder volumes will be same |
| C. | The discharge pressure will be six times suction pressure |
| D. | Temperature rise in the cylinders will be the same |
| E. | Work done in successive stages will be in geometrical progression |
| Answer» D. Temperature rise in the cylinders will be the same | |
| 174. |
The rate of discharge through the nozzle |
| A. | remains same |
| B. | decreases |
| C. | increases |
| E. | None of the above |
| Answer» C. increases | |
| 175. |
A wall 50 mm thick (thermal conductivity k = 40 W/m?C) has temperature difference on two surfaces of 100?C. What could probably change if the temperature difference of this wall drops to 100?C |
| A. | Thickness of wall reduces to 5 mm |
| B. | Thickness of wall increases to 500 mm |
| C. | Thermal conductivity changes to 400 W/?C |
| D. | Rate of heat flow drops to one tenth of the original |
| E. | Area of heat transfer increases 10 times |
| Answer» D. Rate of heat flow drops to one tenth of the original | |
| 176. |
The specific heat at constant volume of solids obeys Deby's T3 law |
| A. | at low pressures |
| B. | at low temperatures |
| C. | at high pressures |
| D. | at all temperatures |
| E. | Pulsejet |
| Answer» D. at all temperatures | |
| 177. |
The temperature, in degrees celsius, at which the colsius scale reading is numerically half the Fahrenheit scale reading is |
| A. | 80?C |
| B. | Pulsejet |
| C. | 42?C |
| D. | 160?C |
| E. | 20?C |
| Answer» D. 160?C | |
| 178. |
A jar contains a mixture of oxygen and hydrogen gas in the ratio 1 : 5. The ratio of mean knetic energies of hydrogen and oxygen molecules is |
| A. | Pulsejet |
| B. | 1 ; 4 |
| C. | 1 ; 1 |
| D. | 1 ; 16 |
| E. | 1 ; 5 |
| Answer» C. 1 ; 1 | |
| 179. |
For any irreversible process the net entropy change is |
| A. | Zero |
| B. | Negative |
| C. | Positive |
| D. | Infinite |
| E. | Unity |
| Answer» C. Positive | |
| 180. |
"Heat can flow from cold substance to hot substance with the aid of external work". Which of the following name is associated with the above statement? |
| A. | Gay Lussac |
| B. | Clausius |
| C. | Planck |
| D. | Kelvin |
| E. | Joule |
| Answer» B. Clausius | |
| 181. |
In which case the work done per kg of air compressed from 1.05 ata, 15?C to 6.3 ata is minimum |
| A. | Polytropic pv1.4 = C |
| B. | Adiabatic |
| C. | Isothermal |
| D. | Polytropic pv1.3 = C |
| E. | Polytropic pv1.35 = C |
| Answer» C. Isothermal | |
| 182. |
The statement that molecular weight of all gases occupy the same volume at NTP is known as |
| A. | Dalton's law |
| B. | Avogadro's hypothesis |
| C. | Joule's law |
| D. | First law of thermodynamics |
| E. | Charle's law |
| Answer» B. Avogadro's hypothesis | |
| 183. |
1 atmospheric pressure is equal to |
| A. | 1.1 kg/cm2 |
| B. | 1.033 kg/cm2 |
| C. | 14.7 kg/cm2 |
| D. | 1 kg/cm2 |
| E. | 1.133 kg/cm2 |
| Answer» B. 1.033 kg/cm2 | |
| 184. |
The relation of the vapour pressure to the enthalpy of vaporization is expressed in |
| A. | Clausius Clapeyron equation |
| B. | Gas equation |
| C. | Energy equation |
| D. | Maxwell's equation |
| E. | Van der Waal's equation |
| Answer» A. Clausius Clapeyron equation | |
| 185. |
During throttling process |
| A. | Pressure does not change |
| B. | Entropy does not change |
| C. | Enthalpy does not change |
| D. | Internal energy does not change |
| E. | Volume change is negligible |
| Answer» C. Enthalpy does not change | |
| 186. |
Which of the following is an extensive property? |
| A. | Pulsejet |
| B. | Viscosity |
| C. | Surface tension |
| D. | Refractive index |
| E. | Heat capacity |
| Answer» E. Heat capacity | |
| 187. |
The charge in a Diesel engine consists of |
| A. | Air + diesel + lubricating oil |
| B. | Diesel + lubricating oil |
| C. | Air + lubricating oil |
| D. | Air |
| E. | Air + diesel |
| Answer» D. Air | |
| 188. |
Which of the following is incorrect? |
| A. | The pressure of a mixture of gases is equal to the sum of the pressure of the individual components taken each at the temperature and volume of the mixture |
| B. | The entropy of a mixture of gases is equal to the sum of the entropies of the individual components taken each at the temperature and volume of the mixture |
| C. | The internal energy of a mixture of gases is equal to the sum f the internal energies of the indicudual components taken each at the temperature and the volume of the mixture |
| D. | (B) and (C) above |
| E. | None of the above |
| Answer» E. None of the above | |
| 189. |
One kg of water is evaporated from 6 kg of sea water containing 4% salt. The percentage of salt in the remaining solution will be |
| A. | 4% |
| B. | 6% |
| C. | 3.33% |
| D. | 4.80% |
| E. | 1% |
| Answer» D. 4.80% | |
| 190. |
In case of real gases, Cp will be equal to Cv |
| A. | Pulsejet |
| B. | at triple point |
| C. | at absolute zero |
| D. | above critical temperature |
| E. | at critical temperature |
| Answer» C. at absolute zero | |
| 191. |
If a surface is elastically hit by N balls each of mass M, moving with same velocity V, the force on the surface will be |
| A. | 2 MNV2 |
| B. | MNV |
| C. | Pulsejet |
| D. | 2 MNV |
| E. | 4 MNV |
| Answer» D. 2 MNV | |
| 192. |
Antifreeze chemicals are |
| A. | Those which lower down the freezing points of liquids |
| B. | Those which do not freeze at all |
| C. | Always in liquid state even at low temperatures |
| D. | Those which are added to refrigerants for better performance |
| E. | Same as refrigerants |
| Answer» A. Those which lower down the freezing points of liquids | |
| 193. |
A carburettor is used to supply |
| A. | Air + lubricating oil |
| B. | Petrol + air |
| C. | Petrol + lubricating oil |
| D. | Petrol + air + lubricating oil |
| E. | Diesel + air + lubricating oil |
| Answer» B. Petrol + air | |
| 194. |
In an adiabatic compression the decrease in volume is associated with |
| A. | Decrease in temperature and increase in pressure |
| B. | Decrease in temperature and decrease in pressure |
| C. | Increase in temperature and decrease in temperature |
| D. | Increase in temperature and increase in pressure |
| E. | None of the above |
| Answer» D. Increase in temperature and increase in pressure | |
| 195. |
A gas having adiabatic index y = 1.4 and atmic weight A will have molecular weight |
| A. | A |
| C. | 2A |
| D. | Pulsejet |
| E. | 3A |
| Answer» C. 2A | |
| 196. |
Identify the incorrect statement |
| A. | The temperature scale is independent of the properties of any substance |
| B. | The size of a unit of temperature, the degree, has a rational interpretation |
| C. | A region of coldest temperature, an absolute zero, is well defined |
| D. | All of the above |
| E. | None of the above |
| Answer» E. None of the above | |
| 197. |
When a bicycle pump is operated slowly the process of compression will be nearly |
| A. | Throttling process |
| B. | Isothermal process |
| C. | Free compression |
| D. | Constant volume process |
| E. | Constant pressure process |
| Answer» B. Isothermal process | |
| 198. |
For water, boiling and melting point will concide at |
| A. | 100? K |
| B. | 216.73? K |
| C. | 200? K |
| D. | 2730.16? K |
| E. | 0? K |
| Answer» D. 2730.16? K | |
| 199. |
1 bar pressure is nearly equal to |
| A. | 13.4 mm Hg |
| B. | 1 mm Hg |
| C. | 100 mm Hg |
| D. | 750 mm Hg |
| E. | 735 mm Hg |
| Answer» D. 750 mm Hg | |
| 200. |
In a Carnot cycle the process which must be carried out at extremely slow speed is |
| A. | adiabatic compression |
| B. | adiabatic expansion |
| C. | isothermal compression |
| D. | None of the above |
| E. | Pulsejet |
| Answer» C. isothermal compression | |
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