MCQOPTIONS
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MCQOPTIONS
This section includes 430 Mcqs, each offering curated multiple-choice questions to sharpen your Thermodynamics knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
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» D. Increases | |
| 302. |
A heat engine works on a Carnot cycle with a heat sink at a temperature of 27?C. The efficiency of the engine is 10%, the temperature of the heat source is |
| A. | 30?C |
| B. | 270?C |
| C. | Temperature shows the extent of expansion |
| D. | 60?C |
| E. | 10?C |
| Answer» E. 10?C | |
| 303. |
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» B. Stalling | |
| 304. |
Which of the following is not a reversible cycle? |
| A. | Carnot cycle |
| B. | Stirling cycle |
| C. | Ericsson cycle |
| D. | Otto cycle |
| E. | All of the above |
| Answer» E. All of the above | |
| 305. |
In a reversible polytropic process |
| A. | Some heat transfer occurs |
| B. | Entropy remains constant |
| C. | Enthalpy remains constant |
| D. | Internal energy remains constant |
| E. | None of the above |
| Answer» B. Entropy remains constant | |
| 306. |
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» D. Polytropic | |
| 307. |
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» C. Isothermal | |
| 308. |
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» D. Pulsejet | |
| 309. |
If during a process, the entropy of the isolated system increases, the process is |
| A. | Adiabatic |
| B. | Ideal |
| C. | Isothermal |
| D. | Reversible |
| E. | Irreversible |
| Answer» F. | |
| 310. |
A liquid flowing through a tube is turbulent. In which case will the maximum change in heat transfer coefficient occur? |
| A. | Diameter of the tube is increased 4 time maintaining the ratio of liquid flow constant |
| B. | Diameter of the tube is increased 4 times maintaining the velocity of flow constant |
| C. | Diameter of the tube is increased 2 times maintaining the rate of liquid flow constant |
| D. | Diameter of the tube is increased 2 times maintaining the velocity of flow constant |
| E. | microns |
| Answer» B. Diameter of the tube is increased 4 times maintaining the velocity of flow constant | |
| 311. |
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» D. Constant volume | |
| 312. |
For a reversible adiabatic process the change in entropy is |
| A. | Unity |
| B. | Zero |
| C. | Maximum |
| D. | Minimum |
| E. | Infinite |
| Answer» C. Maximum | |
| 313. |
In the polytropic process equation pvn Constant, if n = 0 the process is termed as |
| A. | Constant volume |
| B. | Constant pressure |
| C. | Isothermal |
| D. | Constant temperature |
| E. | Adiabatic |
| Answer» C. Isothermal | |
| 314. |
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» D. The product of volume and absolute temperature | |
| 315. |
If a process can be stopped at any stage and reversed so that the system and surroundings are exactly restored to their initial states, it is known as |
| A. | Isothermal process |
| B. | Thermodynamic process |
| C. | Ideal process |
| D. | Adiabatic process |
| E. | Reversible process |
| Answer» F. | |
| 316. |
In any process the maximum amount of mechanical energy that can be converted to heat |
| A. | Depends upon the intake and exhaust temperature |
| B. | Is 50% |
| C. | Depends upon the amount of friction |
| D. | Depends upon whether kinetic energy is involved |
| E. | Is 100% |
| Answer» F. | |
| 317. |
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» E. G = H + Ts | |
| 318. |
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» E. Total heat supplied | |
| 319. |
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» F. | |
| 320. |
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» C. Radiation heat flow only | |
| 321. |
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» E. Exhaust pressure should be high | |
| 322. |
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» F. | |
| 323. |
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» D. ?100?C | |
| 324. |
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» F. | |
| 325. |
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» B. Adiabatic | |
| 326. |
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» D. Decreases | |
| 327. |
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» B. saturated vapours at atmospheric pressure | |
| 328. |
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» C. Pulsejet | |
| 329. |
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» B. 30.4 kg/metre/kg/?K | |
| 330. |
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» C. increase in available heat but decrease in unavailable heat | |
| 331. |
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» E. Two adiabatic and two constant pressure processes | |
| 332. |
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» B. 100 percent | |
| 333. |
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» E. None of the above | |
| 334. |
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» C. Heat transfer occurs from surrounding to system only | |
| 335. |
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» D. 1 ; 16 | |
| 336. |
The melting point of ice |
| A. | Pulsejet |
| B. | decreases with increase in atmospheric pressure |
| C. | increases with increase in atmospheric pressure |
| D. | is independent of atmospheric pressure |
| Answer» C. increases with increase in atmospheric pressure | |
| 337. |
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» E. 0? K | |
| 338. |
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» D. above critical temperature | |
| 339. |
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» E. never lower than the wet bulb temperature | |
| 340. |
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» E. 20?C | |
| 341. |
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» B. Those which do not freeze at all | |
| 342. |
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» E. Pulsejet | |
| 343. |
A gas having adiabatic index y = 1.4 and atmic weight A will have molecular weight |
| A. | A |
| B. | 2A |
| C. | Pulsejet |
| D. | 3A |
| Answer» D. 3A | |
| 344. |
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» E. 4 MNV | |
| 345. |
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» B. Gas equation | |
| 346. |
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» E. 735 mm Hg | |
| 347. |
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» C. Free compression | |
| 348. |
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» D. None of the above | |
| 349. |
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» E. None of the above | |
| 350. |
For any irreversible process the net entropy change is |
| A. | Zero |
| B. | Negative |
| C. | Positive |
| D. | Infinite |
| E. | Unity |
| Answer» D. Infinite | |