McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 51. |
In the polytropic process equation pvn = constant, if the value of n is infinitely large the process is termed as |
| A. | Adiabatic |
| B. | Constant volume |
| C. | Isothermal |
| D. | Constant pressure |
| E. | Constant temperature |
| Answer» B. Constant volume | |
| 52. |
The ratio of the rise in temperature of a gas when compressed adiabatically to that when compressed isothermally to the same extent is |
| A. | More than 1 |
| B. | Less than 1 |
| C. | Equal to 1 |
| D. | Depends on the gas |
| E. | None of the above |
| Answer» A. More than 1 | |
| 53. |
Other factors remaining constant, if the temperature of sink is increased, the efficiency of the Carnot engine will |
| A. | increase or decrease depending upon temperature ratio |
| B. | will not change |
| C. | Pulsejet |
| D. | increase |
| E. | decrease |
| Answer» E. decrease | |
| 54. |
One of the most efficient engines ever developed operates between 2100 k and 700 k. Its actual efficiency is 40%. What percentage of its maximum possible efficiency is this? |
| A. | 40% |
| B. | 33.30% |
| C. | 60% |
| D. | Pulsejet |
| E. | 66.67% |
| Answer» C. 60% | |
| 55. |
For any reversible process, the change in entropy of the system and surroundings is |
| A. | Negative |
| B. | Zero |
| C. | Unity |
| D. | Infinite |
| E. | Positive |
| Answer» B. Zero | |
| 56. |
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» C. Steady flow | |
| 57. |
Entropy of mixing is always |
| A. | positive |
| C. | Zero |
| D. | Negative |
| E. | Pulsejet |
| Answer» A. positive | |
| 58. |
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» D. Homogeneous system | |
| 59. |
An open system |
| A. | Is a specified region where transfers of energy and/or mass take place |
| B. | Is a region of constant mass and only energy is allowed to cross the boundaries |
| C. | Cannot transfer either energy or mass to or from the surroundings |
| D. | Has a mass transfer across its boundaries, and the mass within the system is not necessarily constant |
| E. | None of the above |
| Answer» D. Has a mass transfer across its boundaries, and the mass within the system is not necessarily constant | |
| 60. |
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» E. Part of the steam is withdrawn from the turbine and is used in heating the feed water | |
| 61. |
Which of the following is a path function quantity? |
| A. | Work done |
| B. | Pressure |
| C. | Pulsejet |
| D. | Temperature |
| E. | Enthalpy |
| Answer» A. Work done | |
| 62. |
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» C. 300?C | |
| 63. |
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» D. Is that point where three phases solid, liquid and gas exist together | |
| 64. |
The characteristics of a control volume are |
| A. | The volume shape and position with respect to an observer may change |
| B. | The volume shape and position with respect to an observer are fixed |
| C. | There is no material flow across the boundary |
| D. | Pulsejet |
| E. | There is material flow across the boundary |
| Answer» E. There is material flow across the boundary | |
| 65. |
The gas turbine works on |
| A. | Rankine cycle |
| B. | Brayton cycle |
| C. | Erricson cycle |
| D. | Otto cycle |
| E. | Carnot cycle |
| Answer» B. Brayton cycle | |
| 66. |
All of the following are intensive properties EXCEPT |
| A. | Viscosity |
| B. | Mass |
| C. | Pulsejet |
| D. | Density |
| E. | Temperature |
| Answer» B. Mass | |
| 67. |
A body of weight 100 N falls freely through a distance of 10 m against an atmospheric drag force of 5 N. Considering the body as the system, the work interaction is |
| A. | 1000 Nm |
| B. | Pulsejet |
| C. | 1050 Nm |
| D. | 50 Nm |
| E. | 950 Nm |
| Answer» D. 50 Nm | |
| 68. |
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» B. Does not change | |
| 69. |
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» C. the heat transfer cannot exceed the work done | |
| 70. |
If the dryness fraction of a sample by throttling calorimeter is 0.8 and that by separating calorimeter is also 0.8, then the actual dryness fraction of sample will be taken as |
| A. | Volume change is negligible |
| B. | 1 |
| C. | 0.8 |
| D. | 0.5 |
| E. | 0.64 |
| Answer» E. 0.64 | |
| 71. |
Work done by an expanding gas under adiabatic condition results in |
| A. | Temperature decrease |
| B. | Temperature decreases first and then increase |
| C. | Temperature increase first and then decrease |
| D. | No change in temperature |
| E. | Temperature increase |
| Answer» A. Temperature decrease | |
| 72. |
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» E. Passing alternately steam and air through while hot carbon | |
| 73. |
A process which does not dissipate available energy is known as |
| A. | Isothermal process |
| B. | Energyless process |
| C. | Adiabatic process |
| D. | Ideal process |
| E. | Frictionless process |
| Answer» D. Ideal process | |
| 74. |
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» C. 1.962 kg | |
| 75. |
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» E. Octane number | |
| 76. |
"The internal energy of a gas is a function of temperature". Which of the following name is associated with the above law? |
| A. | Regnault |
| B. | Dalton |
| C. | Boyle |
| D. | Charle |
| E. | Joule |
| Answer» E. Joule | |
| 77. |
The solubility of a gas in a liquid at small concentration is represented by |
| A. | Joules equation |
| B. | Van der Waal's equation |
| C. | Henry's law |
| D. | Claperyon equation |
| E. | Roults law |
| Answer» C. Henry's law | |
| 78. |
A scavenging pump is used in |
| A. | Pulsejet |
| B. | vapour compression cycles |
| C. | two stroke spark ignition engines |
| D. | steam engines |
| E. | four stroke compression ignition engines |
| Answer» C. two stroke spark ignition engines | |
| 79. |
The difference between two specific heats of a gas is equal to universal constant when |
| A. | 1 mole of gas is heated |
| B. | 1 gm molecule of gas is heated |
| C. | 1 gm of gas is heated |
| D. | Pulsejet |
| E. | any amount of gas is heated |
| Answer» B. 1 gm molecule of gas is heated | |
| 80. |
Which of the following is a non-petroleum fuel? |
| A. | Diesel oil |
| B. | Petrol |
| C. | Naphtha |
| D. | Alcohol |
| E. | All of the above |
| Answer» D. Alcohol | |
| 81. |
The average pressure on the walls of a vessel will be doubled if the |
| A. | average velocity of the molecules in it is doubled |
| B. | the number of molecules in the vessel is doubled |
| C. | Pulsejet |
| D. | the mass of each molecule is halved |
| E. | the mass of each molecule is doubled |
| Answer» B. the number of molecules in the vessel is doubled | |
| 82. |
The fastest moving gas molecules are those of |
| A. | Pulsejet |
| B. | Oxygen |
| C. | Hydrogen |
| D. | Nitrogen |
| E. | Chlorine |
| Answer» C. Hydrogen | |
| 83. |
which of the following set of quantities contains intensive variables? |
| A. | Kinetic energy, potential energy and internal energy |
| B. | Pulsejet |
| C. | Work, energy and weight |
| D. | Mass, volume and area |
| E. | Pressure, temperature and density |
| Answer» E. Pressure, temperature and density | |
| 84. |
A system |
| A. | Is a specified region, not necessarily of constant volume, where transfer of energy and/or mass are to be studied |
| B. | Is a region of constant mass and only energy is allowed to cross the boundaries |
| C. | Cannot transfer either energy or mass to or from the surroundings |
| D. | Has a mass transfer across its boundaries and the mass within the system is not constant |
| E. | None of the above |
| Answer» A. Is a specified region, not necessarily of constant volume, where transfer of energy and/or mass are to be studied | |
| 85. |
Transformer oil having kinematic viscosity of 3.66 x 10-6 m2/s flows through a tube 8 mm diameter at velocity of 0.6 m/s. The value of Reynolds number of flow would be |
| A. | 1510 |
| B. | 1000 |
| C. | 1600 |
| D. | 1415 |
| E. | 1310 |
| Answer» E. 1310 | |
| 86. |
An isentropic process is always |
| A. | Irreversible and adiabatic |
| B. | Reversible and isothermal |
| C. | Frictionless and irreversible |
| D. | Reversible and adiabatic |
| E. | None of the above |
| Answer» D. Reversible and adiabatic | |
| 87. |
In a reversible polytropic process |
| A. | The entropy remains constant |
| B. | Some heat transfer occurs |
| C. | The internal energy remains constant |
| D. | The temperature remains constant |
| E. | The ethalpy remains constant |
| Answer» A. The entropy remains constant | |
| 88. |
A gas which obeys kinetic theory perfectly is known as |
| A. | Monoatomic gas |
| B. | Perfect gas |
| C. | Diatomic gas |
| D. | Real gas |
| E. | Pure gas |
| Answer» B. Perfect gas | |
| 89. |
An automobile heats up while lying in a parking 10 ton a sunny day. The process can be assumed to be |
| A. | isothermal |
| B. | isometric |
| C. | isobaric |
| D. | Pulsejet |
| E. | isentropic |
| Answer» C. isobaric | |
| 90. |
The efficiency of a Carnot engine is given as 0.75. If the cycle direction is reversed, what will be the value of COP of reversed Carnot cycle |
| A. | 0.33 |
| B. | 0.25 |
| C. | 1.33 |
| D. | 0.75 |
| E. | 4 |
| Answer» A. 0.33 | |
| 91. |
Which rays have the least wavelength? |
| A. | Infra-red |
| B. | Ultraviolet |
| C. | Radio |
| D. | Cosmic rays |
| E. | X-rays |
| Answer» D. Cosmic rays | |
| 92. |
The difference between two specific heats of a gas is equal to universal gas constant |
| A. | When 1 gm molecule heated |
| B. | When 1 molecule of gas is heated |
| C. | When 1 gm molecule heated |
| D. | When 1 gm of gas is heated |
| E. | When any amount of gas is heated |
| Answer» C. When 1 gm molecule heated | |
| 93. |
1 cu-m of steam having dryness franction 0.85 at 12 ata mixes with 1.5 kg of water at 12?C at constant pressure. The dryness fraction of resulting steam would be |
| A. | 0.6 |
| B. | 0.5 |
| C. | 0.85 |
| D. | 0.637 |
| E. | 0.75 |
| Answer» D. 0.637 | |
| 94. |
In centrifugal compressors, the ratio of outlet whirl velocity to blade velocity at outlet is known as |
| A. | Feedback factor |
| B. | Slip factor |
| C. | Reheat factor |
| D. | Gauge factor |
| E. | Velocity factor |
| Answer» B. Slip factor | |
| 95. |
In case of centrifugal compressors the phenomenon of unsteady, periodic and reversed flow is known as |
| A. | Surging |
| B. | Stalling |
| C. | Choking |
| D. | Either of above |
| E. | None of the above |
| Answer» A. Surging | |
| 96. |
A Rankine cycle working with saturated steam differs thermodynamically from a Carnot cycle only in the fact that |
| A. | The Carnot cycle cannot be used for vapour |
| B. | Steam is not the working substance for Carnot cycle |
| C. | There are more than two sources of heat in Rankine cycle |
| D. | Heat is supplied to the water at temperatures below the maximum temperature of the cycle |
| E. | None of the above |
| Answer» D. Heat is supplied to the water at temperatures below the maximum temperature of the cycle | |
| 97. |
In case of ideal triatomic gas, the ratio of specific heats Cp/Cv would be |
| A. | 1 |
| B. | 1.33 |
| C. | 1.4 |
| D. | 1.41 |
| E. | 1.67 |
| Answer» B. 1.33 | |
| 98. |
During adiabatic expansion which of the following remains constant |
| A. | Internal energy |
| B. | Temperature |
| C. | Entropy |
| D. | None of the above |
| E. | Pulsejet |
| Answer» C. Entropy | |
| 99. |
Which of the following is a boiler accessory? |
| A. | Water level indicator |
| B. | Economiser |
| C. | Pulsejet |
| D. | Stop valve |
| E. | Fusible plug |
| Answer» B. Economiser | |
| 100. |
Draught ensures supply of |
| A. | Air for combustion |
| B. | Feed water |
| C. | Coad to the boiler |
| D. | Superheated steam |
| E. | Isothermal |
| Answer» A. Air for combustion | |
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