MCQOPTIONS
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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.
| 301. |
Carbon dioxide is |
| A. | Colourless |
| B. | Odourless |
| C. | Non-flammable |
| D. | All of these |
| Answer» E. | |
| 302. |
The C.O.P. of a Carnot refrigerator in winter will be _________ as compared to C.O.P. in summer. |
| A. | Same |
| B. | Lower |
| C. | Higher |
| D. | None of these |
| Answer» D. None of these | |
| 303. |
The bank of tubes at the back of domestic refrigerator is |
| A. | Condenser tubes |
| B. | Evaporator tubes |
| C. | Refrigerant cooling tubes |
| D. | Capillary tubes |
| Answer» B. Evaporator tubes | |
| 304. |
As relative humidity decreases, the dew point temperature will be ________ wet bulb temperature. |
| A. | Same as |
| B. | Lower than |
| C. | Higher than |
| D. | None of these |
| Answer» C. Higher than | |
| 305. |
For unsaturated air, the dew point temperature is __________ wet bulb temperature. |
| A. | Equal to |
| B. | Less than |
| C. | More than |
| D. | None of these |
| Answer» C. More than | |
| 306. |
An Electrolux refrigerator is called a _________ absorption system. |
| A. | Single fluid |
| B. | Two fluids |
| C. | Three fluids |
| D. | None of these |
| Answer» D. None of these | |
| 307. |
The mass of water vapour present in __________ is called absolute humidity. |
| A. | 1 m3 of water |
| B. | 1 m3 of dry air |
| C. | 1 kg of wet air |
| D. | 1 kg of dry air |
| Answer» C. 1 kg of wet air | |
| 308. |
The index which correlates the combined effects of air temperature, relative humidity and air velocity on the human body, is known as |
| A. | Mean radiant temperature |
| B. | Effective temperature |
| C. | Dew point temperature |
| D. | None of these |
| Answer» C. Dew point temperature | |
| 309. |
Critical temperature is the temperature above which |
| A. | A gas will never liquefy |
| B. | A gas will immediately liquefy |
| C. | Water will evaporate |
| D. | Water will never evaporate |
| Answer» B. A gas will immediately liquefy | |
| 310. |
The C.O.P. of an absorption type refrigerator is given by (where T₁ = Temperature at which the working substance receives heat, T₂ = Temperature of cooling water, and T₃ = Evaporator temperature) |
| A. | [T₁ (T₂ - T₃)] / [T₃ (T₁ - T₂)] |
| B. | [T₃ (T₁ - T₂)]/ [T₁ (T₂ - T₃)] |
| C. | [T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)] |
| D. | [T₃ (T₂ - T₃)] / [T₁ (T₁ - T₂)] |
| Answer» C. [T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)] | |
| 311. |
Air refrigeration operates on |
| A. | Carnot cycle |
| B. | Reversed Carnot cycle |
| C. | Rankine’s cycle |
| D. | Brayton cycle |
| Answer» E. | |
| 312. |
In aqua ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in |
| A. | Condenser |
| B. | Evaporator |
| C. | Absorber |
| D. | None of these |
| Answer» B. Evaporator | |
| 313. |
While designing the refrigeration system of an aircraft, the prime consideration is that the |
| A. | System has high C.O.P. |
| B. | Power per TR is low |
| C. | Mass of refrigerant circulated in the system is low |
| D. | Mass of the refrigeration equipment is low |
| Answer» E. | |
| 314. |
In S.J. unit, one ton of refrigeration is equal to |
| A. | 210 kJ/ min |
| B. | 21 kJ/ min |
| C. | 420 kJ/ min |
| D. | 840 kJ/ min |
| Answer» B. 21 kJ/ min | |
| 315. |
The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called |
| A. | Kinetic theory of gases |
| B. | Newton's law of gases |
| C. | Dalton's law of partial pressures |
| D. | Avogadro's hypothesis |
| Answer» D. Avogadro's hypothesis | |
| 316. |
In vapour compression refrigeration system, refrigerant occurs as liquid between |
| A. | Condenser and expansion valve |
| B. | Compressor and evaporator |
| C. | Expansion valve and evaporator |
| D. | Compressor and condenser |
| Answer» D. Compressor and condenser | |
| 317. |
Pressure of water vapour is given by |
| A. | 0.622 Pv/ (Pb - Pv) |
| B. | μ/[1 - (1 - μ) (Ps/Pb)] |
| C. | [Pv (Pb - Pd)]/ [Pd (Pb - Pv)] |
| D. | None of these |
| Answer» E. | |
| 318. |
In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is |
| A. | Less than 2 kg |
| B. | More than or equal to 3.65 kg |
| C. | More than 10 kg |
| D. | There is no such consideration |
| Answer» C. More than 10 kg | |
| 319. |
The coefficient of performance is the ratio of the refrigerant effect to the |
| A. | Heat of compression |
| B. | Work done by compressor |
| C. | Enthalpy increase in compressor |
| D. | All of the above |
| Answer» E. | |
| 320. |
The evaporator changes the low pressure liquid refrigerant from the expansion valve into |
| A. | High pressure liquid refrigerant |
| B. | Low pressure liquid and vapour refrigerant |
| C. | Low pressure vapour refrigerant |
| D. | None of these |
| Answer» D. None of these | |
| 321. |
When the lower temperature of a refrigerating machine is fixed, then the coefficient of performance can be improved by |
| A. | Operating the machine at higher speeds |
| B. | Operating the machine at lower speeds |
| C. | Raising the higher temperature |
| D. | Lowering the higher temperature |
| Answer» E. | |
| 322. |
Which of the following statement is correct for ammonia as a refrigerant? |
| A. | It is toxic to mucous membranes. |
| B. | It requires large displacement per TR compared to fluoro carbons. |
| C. | It reacts with copper and its alloys. |
| D. | All of these |
| Answer» E. | |
| 323. |
A vapour absorption refrigerator uses _________ as a refrigerant. |
| A. | Water |
| B. | Ammonia |
| C. | Freon |
| D. | Aqua-ammonia |
| Answer» E. | |
| 324. |
Vertical lines on pressure-enthalpy chart show constant |
| A. | Pressure lines |
| B. | Temperature lines |
| C. | Total heat lines |
| D. | Entropy lines |
| Answer» D. Entropy lines | |
| 325. |
If a heat pump cycle operates between the condenser temperature of +27°C and evaporator temperature of -23°C, then the Carnot COP will be |
| A. | 0.2 |
| B. | 1.2 |
| C. | 5 |
| D. | 6 |
| Answer» E. | |
| 326. |
In vapour compression cycle using NH₃ as refrigerant, initial charge is filled at |
| A. | Suction of compressor |
| B. | Delivery of compressor |
| C. | High pressure side close to receiver |
| D. | Low pressure side near receiver |
| Answer» D. Low pressure side near receiver | |
| 327. |
Ammonia is |
| A. | Non-toxic |
| B. | Non-inflammable |
| C. | Toxic and non-inflammable |
| D. | Highly toxic and inflammable |
| Answer» E. | |
| 328. |
The unit of thermal diffusivity is |
| A. | m/hK |
| B. | m/h |
| C. | m²/h |
| D. | m²/hK |
| Answer» D. m²/hK | |
| 329. |
When the air is passed through an insulated chamber having sprays of water maintained at a temperature higher than the dew point temperature of entering air but lower than its dry bulb temperature, then the air is said to be |
| A. | Cooled and humidified |
| B. | Cooled and dehumidified |
| C. | Heated and humidified |
| D. | Heated and dehumidified |
| Answer» B. Cooled and dehumidified | |
| 330. |
A one tonne refrigerating machine means that |
| A. | One tonne is the total mass of machine |
| B. | One tonne refrigerant is used |
| C. | One tonne of water can be converted into ice |
| D. | One tonne of ice when melts from and at 0° C in 24 hours, the refrigeration effect is equivalent to 210 kJ/min |
| Answer» E. | |
| 331. |
An infinite parallel planes with emissivities e₁ and e₂, the interchange factor for radiation from surface 1 to surface 2 is given by |
| A. | (e₁ + e₂)/ e₁ + e₂ - e₁e₂ |
| B. | 1/e₁ + 1/e₂ |
| C. | e₁ + e₂ |
| D. | e₁e₂ |
| Answer» B. 1/e₁ + 1/e₂ | |
| 332. |
Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system |
| A. | Strong solution to weak solution |
| B. | Weak solution to strong solution |
| C. | Strong solution to ammonia vapour |
| D. | Ammonia vapours to weak solution |
| Answer» C. Strong solution to ammonia vapour | |
| 333. |
The boiling point of ________ is 10.5°C. |
| A. | Ammonia |
| B. | R-12 |
| C. | Sulphur dioxide |
| D. | Carbon dioxide |
| Answer» D. Carbon dioxide | |
| 334. |
During humidification process, __________ increases. |
| A. | Wet bulb temperature |
| B. | Relative humidity |
| C. | Dry bulb temperature |
| D. | Specific humidity |
| Answer» C. Dry bulb temperature | |
| 335. |
During sensible heating of air _________ decreases. |
| A. | Wet bulb temperature |
| B. | Relative humidity |
| C. | Dry bulb temperature |
| D. | Specific humidity |
| Answer» C. Dry bulb temperature | |
| 336. |
In a refrigerating machine, heat rejected is _________ heat absorbed. |
| A. | Equal to |
| B. | Less than |
| C. | Greater than |
| D. | None of these |
| Answer» D. None of these | |
| 337. |
In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is |
| A. | Heated and dehumidified |
| B. | Heated and humidified |
| C. | Cooled and humidified |
| D. | Cooled and dehumidified |
| Answer» C. Cooled and humidified | |
| 338. |
The heat rejection factor (HRF) is given by |
| A. | 1 + C.O.P |
| B. | 1 - C.O.P. |
| C. | 1 + (1/C.O.P) |
| D. | 1 - (1/C.O.P) |
| Answer» D. 1 - (1/C.O.P) | |
| 339. |
Which of the following cycles uses air as the refrigerant? |
| A. | Ericson |
| B. | Stirling |
| C. | Carnot |
| D. | Bell Coleman |
| Answer» E. | |
| 340. |
In a vapour compression system, the condition of refrigerant before passing through the condenser is |
| A. | Saturated liquid |
| B. | Wet vapour |
| C. | Dry saturated vapour |
| D. | Superheated vapour |
| Answer» E. | |
| 341. |
Highest pressure encountered in a refrigeration system should be |
| A. | Critical pressure of refrigerant |
| B. | Much below critical pressure |
| C. | Much above critical pressure |
| D. | Near critical pressure |
| Answer» C. Much above critical pressure | |
| 342. |
The operating pressure for refrigerating units using R-12 as a refrigerant is |
| A. | 2 bar |
| B. | 8 bar |
| C. | 15 bar |
| D. | 30 bar |
| Answer» C. 15 bar | |
| 343. |
The desirable property of a refrigerant is |
| A. | Low boiling point |
| B. | High critical temperature |
| C. | High latent heat of vaporisation |
| D. | All of these |
| Answer» E. | |
| 344. |
The undesirable property of a refrigerant is |
| A. | Non-toxic |
| B. | Non-flammable |
| C. | Non-explosive |
| D. | High boiling point |
| Answer» E. | |
| 345. |
In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = Bypass factor) |
| A. | B.P.F. - 1 |
| B. | 1 - B. P.F. |
| C. | 1/ B.P.F. |
| D. | 1 + B.P.F. |
| Answer» C. 1/ B.P.F. | |
| 346. |
Nusselt number (NN) is given by |
| A. | NN = hl/k |
| B. | NN = μ cp/k |
| C. | NN = ρ V l /μ |
| D. | NN = V²/t.cp |
| Answer» B. NN = μ cp/k | |