McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 301. |
The efficiency of an ideal (Carnot engine) depends on |
| A. | On the temperature of both the source and the sink |
| B. | On the temperature of the source only |
| C. | On the temperature of the sink only |
| D. | On the construction of engine |
| E. | Working substance |
| Answer» A. On the temperature of both the source and the sink | |
| 302. |
A choke is applied in a car |
| A. | For reduction of speed |
| B. | For increasing speed |
| C. | For starting in hot weather |
| D. | For fuel economy |
| E. | For starting in cold weather |
| Answer» E. For starting in cold weather | |
| 303. |
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» A. Some heat transfer occurs | |
| 304. |
Rankine cycle efficiency for a power plant is 29.6%. The Carnot cycle efficiency will be |
| A. | Equal to Rankine cycle efficiency |
| B. | More than Rankine cycle efficiency |
| C. | Less than Rankine cycle efficiency |
| D. | There is no comparison for the two |
| E. | None of the above |
| Answer» B. More than Rankine cycle efficiency | |
| 305. |
The heat flows through solids only by |
| B. | Radiation |
| C. | Conduction |
| D. | microns |
| E. | Convection |
| Answer» C. Conduction | |
| 306. |
Sadi Carnot was a |
| A. | French engineer |
| B. | Russian engineer |
| C. | Pulsejet |
| D. | British engineer |
| E. | German engineer |
| Answer» A. French engineer | |
| 307. |
Cut of ratio in a steam engine is the ratio of |
| A. | Work done by piston after cut off to total work done per cylinder |
| B. | Fraction of piston stroke which the piston has travelled when cut off occurs |
| C. | Pressure at cut off to supply pressure |
| D. | Pressure at cut off to exhaust pressure |
| E. | Pressure at cut off to mean effective pressure |
| Answer» B. Fraction of piston stroke which the piston has travelled when cut off occurs | |
| 308. |
Which of the following statement about Vanc der Waal's equation is valid? |
| A. | Pulsejet |
| B. | It represents a straight line on pv versus v plot |
| C. | The equation is valid for diatomic gases only |
| D. | It is valid for all pressures and temperatures |
| E. | It has three roots of identical value at the critical point |
| Answer» E. It has three roots of identical value at the critical point | |
| 309. |
The statement that the volume of a mixture of ideal gases is equal to the span of the partial volumes which the constituent gases would occupy if each existed alone at the pressure and temperature of the mixture, is known as |
| A. | Clapeyrons law |
| B. | Maxwell's law |
| C. | Leduc's law |
| D. | Daltons law |
| E. | Clausius law |
| Answer» C. Leduc's law | |
| 310. |
Two vessels of volume 5 litres and 3 litres contain air at a pressure of 3 atmospheres and 5 atmospheres respectively. When the two vessels are connected together by a small tube (at constant temperature) the reusltant pressure will be |
| A. | 4.0 atm |
| B. | 5.0 atm |
| C. | 4.5 atm |
| D. | 3.75 atm |
| E. | Pulsejet |
| Answer» D. 3.75 atm | |
| 311. |
The rate of radiant energy, which is emitted by a surface at any temperature and in small wavelengths is found from the known rate of energy, which under the same conditions would be emitted from a black surface, by multiplying with the absorptivity. Above enunciation is known as |
| A. | Planck's law |
| B. | Kirchhoff's law |
| C. | Stefan Bolzmann's law |
| D. | Lambart's rule |
| E. | None of the above |
| Answer» B. Kirchhoff's law | |
| 312. |
A gs which satisfies the Kinetic theory of gases is known as |
| A. | Manoatomic gas |
| B. | Diatomic gas |
| C. | Real gas |
| D. | Perfect gas |
| E. | None of the above |
| Answer» D. Perfect gas | |
| 313. |
Which of the following gas will satisfy, Boyle's law over a wider range of temperatures and pressures? |
| A. | Helium |
| B. | Pulsejet |
| C. | Oxygen |
| D. | Hydrogen |
| E. | Carbon monoxide |
| Answer» A. Helium | |
| 314. |
The term "pre-whirl" is associated with |
| A. | Gas turbines |
| B. | Super-charged diesel engines |
| C. | Sliding vane type air compressors |
| D. | Reciprocating air compressors |
| E. | Centrifugal air compressors |
| Answer» E. Centrifugal air compressors | |
| 315. |
If a heat engine gives an output of 3 kW and input is 10,000 J/s the thermal efficiency of the engine will be |
| A. | 70% |
| B. | 30% |
| C. | 33.30% |
| D. | 66.60% |
| E. | 100% |
| Answer» B. 30% | |
| 316. |
An amount of heat given to a gas under isothermal conditions will be |
| A. | For a temperature rise |
| B. | For doing external work |
| C. | For doing external work and also for a temperature rise |
| D. | For increasing the internal energy of the gas |
| E. | None of the above |
| Answer» B. For doing external work | |
| 317. |
Two gases X and Y having the same temperature T, the same pressure P and the same volume V are mixed. If the mxiture has the volume V and temperature T, then the pressure of the mixture must be |
| A. | 4P |
| B. | P |
| C. | Pulsejet |
| D. | 2P |
| Answer» D. 2P | |
| 318. |
By applying chike in an automobile we get |
| A. | Stoichiometric mixture |
| B. | Chemically correct mixture |
| C. | Weak mixture |
| D. | Lean mixture |
| E. | Rich mixture |
| Answer» E. Rich mixture | |
| 319. |
The critical temperature of carbondioside is 31.1?C. If the room temperature is 34.7?C, then carbondioxide at room temperature is |
| A. | vapour |
| B. | wet vapour |
| C. | Pulsejet |
| D. | superheated vapour |
| E. | gas |
| Answer» E. gas | |
| 320. |
In case of a four cylinder diesel engine, the heat carried away by exhaust gases will be |
| A. | 10 to 20 percent |
| B. | 50 to 70 percent |
| C. | 25 to 35 percent |
| D. | 5 to 7 percent |
| E. | 7 to 10 percent |
| Answer» C. 25 to 35 percent | |
| 321. |
The ratio of enthalpy rise in rotor of a centrifugal compressor to the enthalpy rise in stage is called |
| A. | Adiabatic efficiency |
| B. | Degree of reaction |
| C. | Volumetric efficiency |
| D. | Dynamic pressure ratio |
| E. | Static pressure ratio |
| Answer» B. Degree of reaction | |
| 322. |
During isothermal process |
| A. | Pulsejet |
| B. | supply of heat is accompanied by rise in temperature |
| C. | rise in entropy is accompanied by rise in temperature |
| D. | drop in pressure is accompanied by drop in volume |
| E. | rejection of heat is accompanied by decrease in volume |
| Answer» E. rejection of heat is accompanied by decrease in volume | |
| 323. |
Which of the following relations is not applicable to free expansion process? |
| A. | Heat supplied = Zero |
| B. | Change in internal energy = Zero |
| C. | Change in temperature = Zero |
| D. | Heat rejected = Zero |
| E. | Work done = Zero |
| Answer» C. Change in temperature = Zero | |
| 324. |
Maxwell's thermodynamic relations are valid for |
| A. | Transient conditions only |
| B. | Closed system only |
| C. | Only reversible processes |
| D. | All processes |
| E. | A thermodynamic system in equilibrium |
| Answer» E. A thermodynamic system in equilibrium | |
| 325. |
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» E. Irreversible | |
| 326. |
Kelvin's law deals with |
| A. | conservation of work |
| B. | conservation of heat |
| C. | conversion of work into heat |
| D. | conversion of heat into work |
| E. | Pulsejet |
| Answer» D. conversion of heat into work | |
| 327. |
The processes of a Carnot cycle are |
| A. | Two adiabatic and two constant volume |
| B. | Two constant volume and two isothermals |
| C. | Two isothermals and two isentropics |
| D. | Two adiabatics and two isothermals |
| E. | One constant volume one constant pressure and two isentropics |
| Answer» C. Two isothermals and two isentropics | |
| 328. |
Theoretically in a petrol engine during which stroke both suction as well as exhaust valves will remain closed? |
| A. | Suction stroke |
| B. | Exhaust stroke |
| C. | Both suction and exhaust strokes |
| D. | None of the above |
| E. | Pulsejet |
| Answer» D. None of the above | |
| 329. |
Wavelength is generally measured in |
| A. | microns |
| B. | mm |
| C. | km |
| D. | m |
| E. | cm |
| Answer» A. microns | |
| 330. |
The unit of Universal Gas constant is |
| A. | Dynes/?K |
| B. | erg/?K |
| C. | kcal/?K |
| D. | It is dimensionless |
| E. | W/m?K |
| Answer» B. erg/?K | |
| 331. |
Pipes are insulated so that |
| A. | They may not break under pressure |
| B. | There is minimum corrosion |
| C. | Capacity to withstand pressure is increased |
| D. | Heat loss from the surface is minimized |
| E. | None of the above |
| Answer» D. Heat loss from the surface is minimized | |
| 332. |
The process that follows the equation pvn = constant, is called |
| A. | Adiabatic process |
| B. | Constant pressure process |
| C. | Constant volume process |
| D. | Constant temperature process |
| E. | Polytropic process |
| Answer» E. Polytropic process | |
| 333. |
The total radiant energy emitted by a plane surface per unit area and unit time is called |
| A. | Radiant flux density |
| B. | Total absorptivity |
| C. | Radiant energy |
| D. | Radiant intensity |
| E. | None of the above |
| Answer» A. Radiant flux density | |
| 334. |
Maxwells relations are valid for |
| A. | compressible substances |
| B. | all substances solid, liquid or gas |
| C. | systems of fixed chemical compositions |
| D. | Pulsejet |
| E. | homogeneous as well as heterogeneous systems |
| Answer» A. compressible substances | |
| 335. |
Clog point of an oil is |
| A. | The point of maximum contamination of oil |
| B. | The level of impurities beyond which oil ceases to flow |
| C. | The temperature at which oil solidifies |
| D. | The temperature at which paraffin and waxes in oil start precipitating |
| E. | None of the above |
| Answer» D. The temperature at which paraffin and waxes in oil start precipitating | |
| 336. |
Line's liquifer is based on the principle of |
| A. | Pulsejet |
| B. | Joule-Thomson effect |
| C. | adiabatic magnetisation |
| D. | adiabatic expansion |
| E. | adiabatic demagnetisation |
| Answer» D. adiabatic expansion | |
| 337. |
A process which does not dissipate available energy is known as |
| A. | Adiabatic process |
| B. | Frictionless process |
| C. | Isothermal process |
| D. | Energyless process |
| E. | Ideal process |
| Answer» E. Ideal process | |
| 338. |
Gas laws are applicable to |
| A. | Gases and dry, wet and super-heated vapours |
| B. | Gases only |
| C. | Gases and dry and wet vapours |
| D. | Gases and wet vapours |
| E. | Gases and dry vapours |
| Answer» B. Gases only | |
| 339. |
In an optimum four stage compressor system the first and third stage pressure are 1 kg/cm2 and 9 kg/cm2 respectively what will be the fourth stage delivery pressure? |
| A. | 81 kg/cm2 |
| B. | 27 kg/cm2 |
| C. | 9 kg/cm2 |
| D. | 6 kg/cm2 |
| E. | 3 kg/cm2 |
| Answer» A. 81 kg/cm2 | |
| 340. |
In unsteady state, heat transfer occurs when |
| A. | The body through which heat flow is in motion |
| B. | The source of heat is in motion |
| C. | The heat flow changes with change in temperature |
| D. | The heat flow changes with time |
| E. | None of the above |
| Answer» D. The heat flow changes with time | |
| 341. |
At critical point the latent enthalpy of vaporisation is |
| A. | Only depends on temperature |
| B. | Zero |
| C. | Maximum |
| D. | Minimum |
| E. | None of the above |
| Answer» B. Zero | |
| 342. |
Which of the following relation is not valid for throttling process? |
| A. | Enthalpy before expansion = Enthalpy after expansion |
| B. | Pressure before expansion = pressure after expansion |
| C. | External work done = Zero |
| D. | Mass before expansion = mass after expansion |
| E. | None of the above |
| Answer» B. Pressure before expansion = pressure after expansion | |
| 343. |
The specific heat of a perfect gas is a function of |
| A. | temperature, pressure and entropy only |
| B. | temperature only |
| C. | temperature and pressure only |
| D. | Pulsejet |
| E. | temperature and entropy only |
| Answer» B. temperature only | |
| 344. |
One watt is the same as |
| A. | 100 Nm/s |
| B. | 10 Nm/s |
| C. | 1 Nm/s |
| D. | 1 Nm/min |
| E. | 10 Nm/min |
| Answer» C. 1 Nm/s | |
| 345. |
Within the boiler, the temperature of steam is highest in |
| A. | Super heater |
| B. | Temperature remains constant |
| C. | Water walls |
| D. | Water drum |
| E. | Water tubes |
| Answer» A. Super heater | |
| 346. |
The rate of diffusion along a column of certain cross-sectional area is proportional to the concentration gradient. Above statement is known as |
| A. | Thompson's law |
| B. | Law of diffusion |
| C. | Kirchhoff's law |
| D. | Fick's law |
| E. | None of the above |
| Answer» D. Fick's law | |
| 347. |
1 kgf/cm2 is equal to |
| A. | 776 mm Hg |
| B. | 1 mm Hg |
| C. | 760 mm Hg |
| D. | 735.6 mm Hg |
| E. | 100 mm Hg |
| Answer» D. 735.6 mm Hg | |
| 348. |
If molar Cp = 4.97 then |
| A. | Cv = 2.97 |
| B. | Cv = 0.97 |
| C. | Cv = 5.97 |
| D. | Cv = 0.597 |
| E. | Cv = 1.97 |
| Answer» A. Cv = 2.97 | |
| 349. |
The value of the product of molecular weight and the gas characteristic constant for all gases in kgf m/1 kg mol ?K is |
| A. | 848 |
| B. | 427 |
| C. | 770 |
| D. | 29.27 |
| E. | 30 |
| Answer» B. 427 | |
| 350. |
Isentropic flow is |
| A. | Perfect gas flow |
| B. | Reversible adiabatic flow |
| C. | Ideal fluid flow |
| D. | Irreversible adiabatic flow |
| E. | Frictionaless reversible flow |
| Answer» B. Reversible adiabatic flow | |
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