McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 101. |
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» B. Gas constant in S.I. units | |
| 102. |
The velocity potential exists |
| A. | Only for unidirectional flow |
| B. | Only for rotational flow |
| C. | For all types of continuous flow |
| D. | Only for laminar flow |
| E. | Only for irrotational flow |
| Answer» E. Only for irrotational flow | |
| 103. |
The number of degrees of freedom in case of diatomic gases is |
| A. | 2 |
| B. | 3 |
| C. | 5 |
| D. | 6 |
| E. | 4 |
| Answer» C. 5 | |
| 104. |
Which of the following statement is correct? |
| A. | Both heat and work are path functions |
| B. | Pulsejet |
| C. | Systems never possess heat but work can be |
| D. | While work is a boundary phenomenon heat is not |
| E. | Both heat and work are inexact differentials |
| Answer» A. Both heat and work are path functions | |
| 105. |
Identify the correct statement |
| A. | All substances emit radiation the quality and quantity depends on the absolute temperature and properties of the material composing the radiating body |
| B. | Only some substances emit radiation |
| C. | Quality and quantity of radiation depends on the properties of the material only |
| D. | A substance will emit radiation at a particular wavelength only |
| E. | Bodies black in colour are known as black bodies in radiation |
| Answer» A. All substances emit radiation the quality and quantity depends on the absolute temperature and properties of the material composing the radiating body | |
| 106. |
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» A. Pressure | |
| 107. |
"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» C. Avogadro's hypothesis | |
| 108. |
In which case the heat transferred from the air when compressed from 1.05 ata 15?C to 6.3 ata would be minimum? |
| A. | Adiabatic |
| B. | Polytropic pv1.3 = C |
| C. | Polytropic pv1.31 = C |
| D. | Polytropic pv1.35 = C |
| E. | Isothermal |
| Answer» A. Adiabatic | |
| 109. |
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» D. First decreases, reaches a minimum value and then increases | |
| 110. |
If during a process the entropy of a isolated system increases, the process is |
| A. | Ideal |
| B. | Reversible |
| C. | Irreversible |
| D. | Polytropic |
| E. | None of the above |
| Answer» C. Irreversible | |
| 111. |
The number of processes in a Rankine cycle is |
| A. | Four |
| B. | Five |
| C. | Three |
| D. | Six |
| E. | Two |
| Answer» A. Four | |
| 112. |
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» B. Two isothermals and two constant pressures | |
| 113. |
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» A. Constant pressure | |
| 114. |
Isentropic flow is |
| A. | Irreversible adiabatic flow |
| B. | Ideal fluid flow |
| C. | Change in entropy is zero |
| D. | Frictionless reversible flow |
| E. | Perfect gas flow |
| Answer» C. Change in entropy is zero | |
| 115. |
The triple point for carbondioxide is at about -56.7 C and about 5 atm, pressure. It means that |
| A. | Mass transfer at triple point is maximum |
| B. | When CO2 is exposed to a below 5 atmosphere pressure only solid and liquid phase exist together |
| C. | Above 56.7 C CO2 exists only as a liquid |
| D. | Below 57.7 C CO2 exists only in liquid form |
| E. | When solid CO2 is exposed to 1 atm pressure it begins to change directly to gas |
| Answer» E. When solid CO2 is exposed to 1 atm pressure it begins to change directly to gas | |
| 116. |
In a reversible cycle, the entropy of the system |
| A. | Depends on the properties of working substance |
| B. | Decreases |
| C. | Does not change |
| D. | Increases |
| E. | First increases and then decreases |
| Answer» C. Does not change | |
| 117. |
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» A. Accounts for all energy entering and leaving a control volume | |
| 118. |
The unit of universal gas constant is |
| A. | dynes/?K |
| B. | erg/?K |
| C. | W/m?K |
| D. | kcal/?K |
| E. | W/?K |
| Answer» B. erg/?K | |
| 119. |
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» C. It will freeze mercury and ammonia | |
| 120. |
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» B. dS = 0 | |
| 121. |
According to Amagat's law |
| A. | the sum of the volume friction is unity |
| B. | there would be no volume change if the components are mixed while holding the temperature and pressure constant |
| C. | all diatomic gases occupy double the volume of monoatomic gases for identical masses |
| D. | None of the above |
| E. | Pulsejet |
| Answer» A. the sum of the volume friction is unity | |
| 122. |
In the polytropic process pvn = Constant if n = 1 the process is termed as |
| A. | Adiabatic |
| B. | Constant pressure |
| C. | Constant temperature |
| D. | Constant volume |
| E. | Isothermal |
| Answer» C. Constant temperature | |
| 123. |
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» A. Two isentropics and two constant volumes | |
| 124. |
If the two specific heats of a gas are 0.237 and 0.169 respectively, the volume of 3 kg of air at 27?C under a pressure of 3 ata would be |
| A. | 2.5 cu-m |
| B. | 1 cu-m |
| C. | 0.204 cu-m |
| D. | 1.74 cu-m |
| E. | 1.5 cu-m |
| Answer» C. 0.204 cu-m | |
| 125. |
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» C. 70 kg | |
| 126. |
A substance above critical temperature exists as |
| A. | Solid |
| B. | Liquid |
| C. | Gas |
| D. | Unsaturated vapour |
| E. | Any of the above |
| Answer» C. Gas | |
| 127. |
In the above problem work done is equal to |
| A. | 130 kcal |
| B. | 150 kcal |
| C. | 100 kcal |
| D. | 80 kcal |
| E. | 180 kcal |
| Answer» D. 80 kcal | |
| 128. |
In a boiler a fusible plug is located at the |
| A. | Pulsejet |
| B. | inlet to stop valve |
| C. | top of superheater |
| D. | bottom of drum |
| E. | bottom of fire tubes |
| Answer» E. bottom of fire tubes | |
| 129. |
For maximum specific output of a constant volume cycle |
| A. | The working fluid should be air |
| B. | The speed should be high |
| C. | Suction temperature should be high |
| D. | Temperature of the working fluid at the end of compression and expansion should be equal |
| E. | Exhaust pressure should be high |
| Answer» D. Temperature of the working fluid at the end of compression and expansion should be equal | |
| 130. |
A frictionless heat engine can be 100% efficient only if its exhaust temperature is |
| A. | Equal to its input temperature |
| B. | Less than its input temperature |
| C. | 0?K |
| D. | ?100?C |
| E. | 0?C |
| Answer» C. 0?K | |
| 131. |
In steam tables, the entropy is shown as zero for |
| A. | saturated liquid at 0?C |
| B. | saturated vapours at atmospheric pressure |
| C. | Pulsejet |
| D. | saturated vapour at 0?C |
| E. | saturated liquid at atmospheric pressure |
| Answer» A. saturated liquid at 0?C | |
| 132. |
When a gas is to be stored, the type of compression that would be ideal is |
| A. | Isothermal |
| B. | Adiabatic |
| C. | Polytropic |
| D. | Constant pressure |
| E. | None of the above |
| Answer» A. Isothermal | |
| 133. |
Diffusion is |
| A. | Mixing of two portions of fluid |
| B. | Mixing of a gas in two containers at different pressures |
| C. | Mixing of two portions of a fluid at different temperatures |
| D. | Mixing of unlike fluids |
| E. | None of the above |
| Answer» D. Mixing of unlike fluids | |
| 134. |
In case the temperature of a hot body is increased by 50%, the amount of radiation emitted by it would increase by nearly |
| A. | 250% |
| B. | 500% |
| C. | Pulsejet |
| D. | 50% |
| E. | 125% |
| Answer» B. 500% | |
| 135. |
The efficiency of cycle would be |
| A. | 66.7 percent |
| B. | 100 percent |
| C. | 88.8 percent |
| D. | 37.7 percent |
| E. | 78.3 percent |
| Answer» A. 66.7 percent | |
| 136. |
If the temperature of the sink is decreased, the efficiency of a Carnot engine |
| A. | remain unaffected |
| B. | first increased and then decreases |
| C. | Pulsejet |
| D. | decreases |
| E. | increases |
| Answer» E. increases | |
| 137. |
When a gas is to be stored, the type of compression that would be ideal is |
| A. | Isothermal |
| B. | Adiabatic |
| C. | Polytropic |
| D. | Constant volume |
| E. | None of the above |
| Answer» A. Isothermal | |
| 138. |
According to Lussac's law for perfect gases, the absolute pressure of given mass varies directly as |
| A. | Temperature |
| B. | Absolute temperature |
| C. | Absolute temperature in case the volume remains constant |
| D. | The product of volume and absolute temperature |
| E. | None of the above |
| Answer» C. Absolute temperature in case the volume remains constant | |
| 139. |
Gibbs free energy G is given by |
| A. | G = T . H . s. |
| B. | G = H/Ts |
| C. | Pulsejet |
| D. | G = H - Ts |
| E. | G = H + Ts |
| Answer» D. G = H - Ts | |
| 140. |
A sterling cycle consists of |
| A. | Two isothermal and two adiabatic processes |
| B. | Two constant volume and two constant pressure processes |
| C. | Two adiabatic and two isentropic processes |
| D. | Two isothermal and two constant volume processes |
| E. | Two adiabatic and two constant pressure processes |
| Answer» D. Two isothermal and two constant volume processes | |
| 141. |
A reversible process requires that |
| A. | Newton's law of viscosity be satisfied |
| B. | There whould be no viscous or coulomb friction in the system |
| C. | Heat transfer occurs from surrounding to system only |
| D. | Temperature of system and surroundings be equal |
| E. | There be no heat transfer |
| Answer» B. There whould be no viscous or coulomb friction in the system | |
| 142. |
The area of pv diagram for a Carnot cycle represents |
| A. | Enthalpy drop |
| B. | Volume and pressure ratios. |
| C. | Temperature drop |
| D. | Work done |
| E. | Total heat supplied |
| Answer» D. Work done | |
| 143. |
An adlabatic wall permits |
| A. | Heat exchange by all the three modes of heat transfer |
| B. | No heat exchange |
| C. | Radiation heat flow only |
| D. | Convective heat flow only |
| E. | Conduction heat flow only |
| Answer» B. No heat exchange | |
| 144. |
The melting point of ice |
| A. | Pulsejet |
| B. | decreases with increase in atmospheric pressure |
| C. | increases with increase in atmospheric pressure |
| E. | is independent of atmospheric pressure |
| Answer» B. decreases with increase in atmospheric pressure | |
| 145. |
In an isothermal process change in internal energy |
| A. | Depends on the friction and other factors |
| B. | Becomes zero |
| C. | Remains constant |
| D. | Decreases |
| E. | Increases |
| Answer» C. Remains constant | |
| 146. |
When two gases are not under the same conditions of temperature and pressure, upon mixing there will be |
| A. | loss of entropy to the surroundings |
| B. | exchange of entropy between the two gases |
| C. | increase in available heat but decrease in unavailable heat |
| D. | None of the above |
| E. | Pulsejet |
| Answer» B. exchange of entropy between the two gases | |
| 147. |
The dew point temperature of humid air is |
| A. | the temperature of air obtained on cooling it till saturation at constant volume |
| B. | Pulsejet |
| C. | always higher than the wet bulb temperature |
| D. | the temperature of air obtained on cooling it till saturation at constant pressure |
| E. | never lower than the wet bulb temperature |
| Answer» D. the temperature of air obtained on cooling it till saturation at constant pressure | |
| 148. |
Which one of the following is heterogeneous system |
| A. | Cooking gas in a cylinder |
| B. | The cooling fluid in the radiator |
| C. | A mixture of hydrogen and oxygen |
| D. | Atmospheric air |
| E. | A mixture of ice, water and system. |
| Answer» E. A mixture of ice, water and system. | |
| 149. |
The value of characteristic gas constant for carbon dioxide would be |
| A. | 19.28 kg/metre/kg/?K |
| B. | 30.4 kg/metre/kg/?K |
| C. | 29.2 kg/metre/kg/?K |
| D. | 16.1 kg/metre/kg/?K |
| E. | 10.0 kg/metre/kg/?K |
| Answer» A. 19.28 kg/metre/kg/?K | |
| 150. |
In case of centrifugal compressors the phenomenon of fixed mass flow rate in compressor regardless of pressure ratio is known as |
| A. | Choking |
| B. | Stalling |
| C. | Recirculation |
| D. | Surging |
| E. | Regeneration |
| Answer» A. Choking | |
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