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MCQOPTIONS
This section includes 346 Mcqs, each offering curated multiple-choice questions to sharpen your GATE (Mechanical Engineering) knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Presence of moisture in a refrigerant affects the working of |
| A. | Compressor |
| B. | Condenser |
| C. | Evaporator |
| D. | Expansion valve |
| Answer» E. | |
| 102. |
The cooling system used for supersonic aircrafts and rockets is |
| A. | Simple air cooling system |
| B. | Bootstrap air cooling system |
| C. | Reduced ambient air cooling system |
| D. | Regenerative air cooling system |
| Answer» E. | |
| 103. |
A refrigerant with the highest critical pressure is |
| A. | R-11 |
| B. | R-12 |
| C. | R-22 |
| D. | Ammonia |
| Answer» E. | |
| 104. |
In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is |
| A. | High pressure saturated liquid |
| B. | Wet vapour |
| C. | Very wet vapour |
| D. | Dry vapour |
| Answer» B. Wet vapour | |
| 105. |
Wet bulb temperature is the temperature of air recorded by a thermometer, when |
| A. | It is not affected by the moisture present in the air |
| B. | Its bulb is surrounded by a wet cloth exposed to the air |
| C. | The moisture present in it begins to condense |
| D. | None of the above |
| Answer» C. The moisture present in it begins to condense | |
| 106. |
Dry bulb temperature is the temperature of air recorded by a thermometer, when |
| A. | It is not affected by the moisture present in the air |
| B. | Its bulb is surrounded by a wet cloth exposed to the air |
| C. | The moisture present in it begins to condense |
| D. | None of the above |
| Answer» B. Its bulb is surrounded by a wet cloth exposed to the air | |
| 107. |
Which of the following refrigerant has the maximum ozone depletion potential in the stratosphere? |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | Fluorine |
| Answer» E. | |
| 108. |
In air-conditioning of aeroplanes, using air as a refrigerant, the cycle used is |
| A. | Reversed Carnot cycle |
| B. | Reversed Joule cycle |
| C. | Reversed Brayton cycle |
| D. | Reversed Otto cycle |
| Answer» D. Reversed Otto cycle | |
| 109. |
The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the cooling coil, and td₃ = Dry bulb temperature of the cooling coil) |
| A. | (td₁ -td₃)/( td₂ -td₃) |
| B. | (td₂ -td₃)/( td₁ -td₃) |
| C. | (td₃ -td₁)/( td₂ -td₃) |
| D. | (td₃ -td₂)/( td₁ -td₃) |
| Answer» C. (td₃ -td₁)/( td₂ -td₃) | |
| 110. |
Short horizontal lines on pressure-enthalpy chart show |
| A. | Constant pressure lines |
| B. | Constant temperature lines |
| C. | Constant total heat lines |
| D. | Constant entropy lines |
| Answer» B. Constant temperature lines | |
| 111. |
The colour of the flame of halide torch, in case of leakage of Freon refrigerant, will change to |
| A. | Bright green |
| B. | Yellow |
| C. | Red |
| D. | Orange |
| Answer» B. Yellow | |
| 112. |
Which of the following refrigerants has lowest freezing point? |
| A. | Freon-12 |
| B. | NH3 |
| C. | CO2 |
| D. | Freon-22 |
| Answer» E. | |
| 113. |
Which of the following refrigerant has the lowest freezing point? |
| A. | R-11 |
| B. | R-12 |
| C. | R-22 |
| D. | Ammonia |
| Answer» D. Ammonia | |
| 114. |
Which of the following refrigerant has the highest freezing point. |
| A. | Ammonia |
| B. | Carbon dioxide |
| C. | Sulphur dioxide |
| D. | R-12 |
| Answer» C. Sulphur dioxide | |
| 115. |
Accumulators should have adequate volume to store refrigerant charge at least |
| A. | 10% |
| B. | 25% |
| C. | 50% |
| D. | 75% |
| Answer» D. 75% | |
| 116. |
The COP of a domestic refrigerator |
| A. | Is less than 1 |
| B. | Is more than 1 |
| C. | Is equal to 1 |
| D. | Depends upon the make |
| Answer» C. Is equal to 1 | |
| 117. |
The lowest temperature during the cycle in a vapour compression system occurs after |
| A. | Compression |
| B. | Expansion |
| C. | Condensation |
| D. | Evaporation |
| Answer» E. | |
| 118. |
During sensible cooling of air, specific humidity |
| A. | Remains constant |
| B. | Increases |
| C. | Decreases |
| D. | None of these |
| Answer» B. Increases | |
| 119. |
Rating of a domestic refrigerator is of the order of |
| A. | 0.1 ton |
| B. | 5 tons |
| C. | 10 tons |
| D. | 40 tons |
| Answer» B. 5 tons | |
| 120. |
Allowable pressure on high pressure side or ammonia absorption system is of the order of |
| A. | Atmospheric pressure |
| B. | Slightly above atmospheric pressure |
| C. | 24 bars |
| D. | 56 bars |
| Answer» E. | |
| 121. |
Mass flow ratio of NH₃ in comparison to Freon-12 for same refrigeration load and same temperature limits is of the order of |
| A. | 1: 1 |
| B. | 1: 9 |
| C. | 9: 1 |
| D. | 1: 3 |
| Answer» C. 9: 1 | |
| 122. |
The capacity of a domestic refrigerator is in the range of |
| A. | 0.1 to 0.3 TR |
| B. | 1 to 3 TR |
| C. | 3 to 5 TR |
| D. | 5 to 7 TR |
| Answer» B. 1 to 3 TR | |
| 123. |
When the temperature of the surrounding is higher than the temperature of the body, then the heat loss by convection from the body to the surrounding will be |
| A. | Positive |
| B. | Negative |
| C. | Zero |
| D. | None of these |
| Answer» C. Zero | |
| 124. |
During sensible cooling, |
| A. | Relative humidity remains constant |
| B. | Wet bulb temperature increases |
| C. | Specific humidity increases |
| D. | Partial pressure of vapour remains constant |
| Answer» E. | |
| 125. |
Efficiency of a Carnot engine is given as 80%. If the cycle direction be reversed, what will be the value of C.O.P. of reversed Carnot Cycle? |
| A. | 1.25 |
| B. | 0.8 |
| C. | 0.5 |
| D. | 0.25 |
| Answer» E. | |
| 126. |
In vapour compression cycle, the condition of refrigerant is very wet vapour |
| A. | After passing through the condenser |
| B. | Before passing through the condenser |
| C. | After passing through the expansion or throttle valve |
| D. | Before entering the compressor |
| Answer» E. | |
| 127. |
In aircraft, air refrigeration Cycle is used because of |
| A. | Low weight per tonne of refrigeration |
| B. | High heat transfer rate |
| C. | Low temperature at high altitudes |
| D. | Higher coefficient of performance |
| Answer» B. High heat transfer rate | |
| 128. |
Condensing temperature in a refrigerator is the temperature |
| A. | Of cooling medium |
| B. | Of freezing zone |
| C. | Of evaporator |
| D. | At which refrigerant gas becomes liquid |
| Answer» E. | |
| 129. |
The evolution of heat of solution takes place in ammonia absorption plant when |
| A. | Ammonia vapour goes into solution |
| B. | Ammonia vapour is driven out of solution |
| C. | Lithium bromide mixes with ammonia |
| D. | Weak solution mixes with strong solution |
| Answer» B. Ammonia vapour is driven out of solution | |
| 130. |
The alignment circle is marked on the psychrometric chart at |
| A. | 20°C DBT and 50% RH |
| B. | 26°C DBT and 50% RH |
| C. | 20°C DBT and 60% RH |
| D. | 26°C DBT and 60% RH |
| Answer» C. 20°C DBT and 60% RH | |
| 131. |
The operating temperature of a cold storage is -2°C. The heat leakage from the surrounding is 30 kW for the ambient temperature of 40°C. The actual C.O.P. of refrigeration plant used is one fourth that of ideal plant working between the same temperatures. The power required to drive the plant is |
| A. | 1.86 kW |
| B. | 3.72 kW |
| C. | 7.44 kW |
| D. | 18.6 kW |
| Answer» E. | |
| 132. |
In a lithium bromide absorption refrigeration system |
| A. | Lithium bromide is used as a refrigerant and water as an absorbent |
| B. | Water is used as a refrigerant and lithium bromide as an absorbent |
| C. | Ammonia is used as a refrigerant and lithium bromide as an absorbent |
| D. | None of the above |
| Answer» C. Ammonia is used as a refrigerant and lithium bromide as an absorbent | |
| 133. |
Most of the domestic refrigerators work on the following refrigeration system |
| A. | Vapour compression |
| B. | Vapour absorption |
| C. | Carnot cycle |
| D. | Electrolux refrigerator |
| Answer» B. Vapour absorption | |
| 134. |
At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant |
| A. | decreases |
| B. | increases |
| C. | remains same |
| D. | depends on other factors |
| Answer» C. remains same | |
| 135. |
Vapour compression refrigeration is somewhat like |
| A. | Carnot cycle |
| B. | Reversed Carnot cycle |
| C. | None of the above |
| D. | |
| Answer» E. | |
| 136. |
In a refrigeration cycle, the flow of refrigerant is controlled by |
| A. | Compressor |
| B. | Condenser |
| C. | Evaporator |
| D. | Expansion valve |
| Answer» E. | |
| 137. |
An evaporator is also known as |
| A. | Freezing coil |
| B. | Cooling coil |
| C. | Chilling coil |
| D. | All of these |
| Answer» E. | |
| 138. |
The optimum effective temperature for human comfort is |
| A. | Higher in winter than in summer |
| B. | Lower in winter than in summer |
| C. | Same in winter and summer |
| D. | Not dependent on season |
| Answer» C. Same in winter and summer | |
| 139. |
Aqua ammonia is used as refrigerant in the following type of refrigeration system |
| A. | Compression |
| B. | Direct |
| C. | Indirect |
| D. | Absorption |
| Answer» E. | |
| 140. |
A thermostatic expansion valve in a refrigeration system |
| A. | Ensures the evaporator completely filled with refrigerant of the load |
| B. | Is suitable only for constant load systems |
| C. | Maintains different temperatures in evaporator in proportion to load |
| D. | None of the above |
| Answer» B. Is suitable only for constant load systems | |
| 141. |
A refrigeration system |
| A. | Removes heat from a low temperature body and delivers it to a high temperature body |
| B. | Removes heat from a high temperature body and delivers it to a low temperature body |
| C. | Rejects energy to a low temperature body |
| D. | None of the above |
| Answer» B. Removes heat from a high temperature body and delivers it to a low temperature body | |
| 142. |
A vapour absorption refrigeration system |
| A. | Gives noisy operation |
| B. | Gives quiet operation |
| C. | Requires little power consumption |
| D. | Cools below 0°C |
| Answer» C. Requires little power consumption | |
| 143. |
In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the |
| A. | Expansion valve to the evaporator |
| B. | Evaporator to the thermostat |
| C. | Condenser to the expansion valve |
| D. | Condenser to the evaporator |
| Answer» B. Evaporator to the thermostat | |
| 144. |
A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating machine with all other conditions unchanged, the coefficient of performance will be |
| A. | 1.33 |
| B. | 2.33 |
| C. | 3.33 |
| D. | 4.33 |
| Answer» C. 3.33 | |
| 145. |
A refrigerant compressor is used to |
| A. | Raise the pressure of the refrigerant |
| B. | Raise the temperature of the refrigerant |
| C. | Circulate the refrigerant through the refrigerating system |
| D. | All of the above |
| Answer» E. | |
| 146. |
In a flooded evaporator refrigerator, an accumulator at suction of compressor is used to |
| A. | Collect liquid refrigerant and prevent it from going to compressor |
| B. | Detect liquid in vapour |
| C. | Superheat the vapour |
| D. | Collect vapours |
| Answer» B. Detect liquid in vapour | |
| 147. |
The temperature of ammonia after compression in a vapour compression system is |
| A. | 20 to 50°C |
| B. | 50 to 70°C |
| C. | 70 to 110°C |
| D. | None of these |
| Answer» D. None of these | |
| 148. |
The condition of refrigerant as it leaves the compressor in a vapour compression system is |
| A. | Saturated liquid |
| B. | Wet vapour |
| C. | Dry saturated vapour |
| D. | Superheated vapour |
| Answer» E. | |
| 149. |
The condition of refrigerant after passing through the condenser in a vapour compression system is |
| A. | Saturated liquid |
| B. | Wet vapour |
| C. | Dry saturated vapour |
| D. | Superheated vapour |
| Answer» B. Wet vapour | |
| 150. |
During dehumidification process, _________ remains constant. |
| A. | Wet bulb temperature |
| B. | Relative humidity |
| C. | Dry bulb temperature |
| D. | Specific humidity |
| Answer» D. Specific humidity | |