Mechanical Engineering MCQs Quiz Multiple Choice Questions & Answers

1. Work is considered positive when

1. Work is done on the system
2. work is done by the system
3. both a and b
4. none of the above

2. A source of energy is known as renewable source

1. Fossil fuel
2. Solar
3. CNG
4. All of the above

3. 1 inch is equals to how many centimeters?

1. 2.5
2. 2.46
3. 2.54
4. 2.58

4. 1 kg/cm² = ........bar

1. 0.981
2. 9.81
3. 98.1
4. 981

5. A device which is used for pumping the water in boiler is

1. Feed check valve
2. Economi ser
3. Injector
4. Feed Pump

6. A device which is used for remove the impurities from the boiler is called

1. Economizer
2. Feed pump
3. Injector
4. Blow-off-cock

7. A system in which there is no transfer of mass across its boundaries is called

1. Closed system
2. Open system
3. Isolated system
4. None of this

8. A unit consists Of closed vessel, economizer, super heater, water wall tubes and it producing steam as per requirement called.

1. Boiler
2. Power plant
3. Steam generator
4. l.c. engine

9. Air vessel is used in

1. Centrifugal Pump
2. Vane pump
3. Gear pump
4. Single acting Reciprocating.

10. An isothermal process is governed by

1. Boyles law
2. Gay-Lussac law
3. Charles law
4. Avogadros law

11. CNG is an excellent for

1. petrol engine
2. Kerosene engine
3. Diesel engine
4. All of above

12. Cochran boiler is .

1. Vertical boiler
2. Natural circulation boiler
3. Fire tube boiler
4. All Of above

13. Compressor in which compression of air from suction pressure to delivery pressure takes place in more than one cylinder is called compressor.

1. Single acting
2. Double acting
3. Single stage
4. Multi stage

14. Compressor is a machine which is used to do

1. lift liquid from low height to higher elevation
2. To store liquid
3. To compress gas.
4. none of the above

15. Dryness fraction of wet steam is

1. greater than 1
2. less than 1
3. #NAME?

16. During adiabatic process

1. heat transfer is zero
2. enthalpy remains constant
3. work transfer is zero
4. enthalpy change is zero.

17. During compression process which parameter will change?

1. Pressure
2. Volume
3. Density
4. All Of above

18. For earth moving machines, widely used engines are:

1. Petrol engine
2. Steam engine
3. Diesel engine
4. Gas engine

19. Function of piston rings is

1. To connect piston and connecting road
2. To transmit force from piston to crank
3. To maintain a gas tight between the piston and the cylinder
4. To convert reciprocating motion into rotary motion

20. If xl and x2 are the dryness fractions obtained in separating calorimeter and throttling calorimeter respectively, then actual dryness fraction of steam is

1. XI - X2
2. XI + X2 /2
3. X1 + X2
4. X1 * X2

21. In a IC engine from which of the following source energy is converted into mechanical energy

1. Chemical energy of fuel.
2. potential energy
3. kinetic energy
4. All of the above

22. In a simple gear train having two gears, if driving gear rotates in clockwise direction then driven gear rotates in

1. Clockwise direction
2. Anti clockwise direction
3. Depend on size of gear
4. depend on no. of teeth

23. In a two stroke cycle engine, one cycle is completed in the following number of revolutions of the crank shaft

1. 2
2. 3
3. 1
4. 4

24. In diesel cycle, heat is added at

1. constant temperature
2. constant enthalpy
3. constant volume
4. constant pressure

25. In Following which is the power producing device?

1. Pump
2. I.C. Engine
3. Compressor
4. Air Conditioner

26. In multi stage compression as compared to single stage compression the volumetric efficiency is

1. more
2. less
3. Constant
4. None of the above

27. In S.I. unit for the force is.

1. Kgm
2. Kgf
3. Newton
4. Lb

28. In the Polytropic Process PVⁿ= C, if n = infinity , the process is called

1. isochoric
2. isobaric
3. isothermal
4. adiabatic

29. Main disadvantage of nuclear energy is

1. High operating cost
2. Low efficiency
3. Waste disposal
4. All of above

30. Natural fuel is

1. That occur in nature
2. Known as secondary fuel
3. Prepared fuel
4. None of the above

31. Petroleum is

1. Solid fuel
2. Liquid fuel
3. Secondary fuel
4. None of this

32. Pump is a machine which is used to do

1. lift liquid from low height to higher elevation
2. To store liquid
3. To compress liquid
4. none of the above

33. Reducing pressure angle on gears results in

1. Weaker teeth
2. Stronger teeth
3. High velocity ratio
4. High efficiency

34. Saturation temperature of steam increase

1. With decrease in pressure
2. with increase in pressure
3. is unaffected by pressure
4. none of the above

35. Specific heat is defined as the amount of heat required

1. To raise unit of temp of a substance
2. To raise unit mass of substance through unit degree of temperature
3. To raise unit mass of substance through 100 C
4. None of this

36. The ability of a material to resist fracture due to high impact loads is called

1. strength
2. stiffness
3. toughness
4. brittleness

37. The air standard cycle on which the petrol engine work is

1. Otto cycle
2. Carrot cycle
3. Joule cycle
4. Dual cycle

38. The cam shaft speed of four stroke engine is

1. Double than crank shaft speed
2. Four times of crank shaft speed
3. Equal to crank shaft speed
4. Half of crank shaft speed

39. The clearance volume in a compressor is provided

1. To increase volumetric efficiency
2. to reduce the work input
3. So that piston does no strike the cylinder head
4. To accommodate valves in the cylinder

40. The clutch ordinarily remains in disengaged condition when it is used for power transmission in:

1. Automobile
2. Machine tools
3. Crane
4. Elevator

41. The compression ratio for the diesel engine is approximately in the following range

1. 5:1 to 10:1
2. 11:1 to 20:1
3. 12:1 to 15:1
4. 10:1 to 12:1

42. The correct location of economizer is :

1. Between furnace and preheater
2. between forced draft fan and furnace
3. between airpreheater and chimney
4. near the superheater

43. The following is the one of the characteristics of I.C. engine

1. Large in size
2. Cheaper fuel may be used
3. Starting is difficult
4. More efficient

44. The function of boiler is

1. To compressed steam
2. To generate steam at a desired pressure
3. To heat feed water
4. To blow out hot gases.

45. The function of ozone layer is

1. protects the earth from harmful effect of ultraviolet rays
2. increase the temperature of earth
3. increases CO2 in atmosphere
4. none of the above

46. The function of steam stop valve is

1. TO regulate flow Of steam from boiler to steam pipe
2. TO separate steam from water
3. TO collect steam from drum
4. TO provide safety of boiler

47. The main function Of an automobile gearbox is

1. to reduce speed
2. to increase speed
3. to provide variable speeds
4. to increase power

48. The moving part of a centrifugal pump is called a

1. Impeller
2. Volute
3. Diffuser
4. Suction nozzle

49. The process of sublimation is found to occur in

1. Liquid N2
2. Solid CO₂
3. Solid 0₂
4. Air

50. The processes of Carrot cycle are

1. Two adiabatic and two constant volume
2. Two constant pressure and two constant volume
3. Two isothermal and two adiabatic
4. Two isothermal and two isentropic