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### Heat and Thermodynamics - MCQs

Heat and Thermodynamics - MCQs Points : Heat and Thermodynamics - mcqs, Heat and Thermodynamics fill in the blanks, mechanics objective type questions 1. Temperature of a block of iron is 140°F. Its temperature on the celsius scale will be
(a) 20°
(b) 40°
(c) 60°
(d) 80°

2. In the equation PV=RT, V stands for the volume of
(a) 1 litre of gas
(b) one gram of gas
(c) any amount of gas
(d) one gm molecules of a gas

3. Ttemperature at which centigrade and Farenheit scales give the similar reading is
(a) 128°C
(b) 32° F
(c) -40°C
(d) -108°C

4. Resistance of a resistance thermometer has values 2.71 and 3.70 ohms at 10°C and 100°C in that order. The temperature at which the resistance is 3.26 ohms is
(a) 30°C
(b) 40°C
(c) 50°C
(d) 60°C

5. Intended for Boyle’s law to hold good, the gas should be
(a) real and at constant temperature but variable mass
(b) perfect and at constant temperature but changeable mass
(c) real and of constant mass and temperature
(d) perfect and of constant mass and temperature

6. We mark the relation for Boyle’s law in the type PV = C when the tempera lure ruins constant. In this relation, magnitude of C depends upon
(a) the quantity of the gas enclosed
(b) the atmospheric pressure
(c) the nature of the gas used in the experiment
(d) the magnitude of g in the laboratory

7. Gas thermometers are further sensitive then liquid thermometers as
(a) gases are much lighter
(b) gases are much heavier
(c) expansion of gases is more than liquids
(d) gases are easy to obtain

8. Below which of the follow conditions is the law PV=RT obeyed by a real gas?
(a) High pressure and low temperature
(b) Low pressure and high temperature
(c) Low pressure and low temperature
(d) High pressure and high temperature

9. If temperature of a patient is 40°C this temperature on farenheit scale will be
(a) 98.4°F
(b) 100°F
(c) 104°F
(d) 110°F

10. Charle’s law holds good for an ideal gas during an
(a) isothermal change
(b) isochoric change
(c) isotopic change
(d) isobaric change

11. Dissimilar thermometers of similar type give dissimilar measurements of the temperature of same body. The variations are smallest in the case of
(a) bimetallic thermometers
(b) thermocouple thermometers
(c) gas thermometers
(d) liquid-in gas thermometers

12. Expansion during heating
(a) decreases the density of a material
(b) increases the weight of a material
(c) occurs in solids
(d) occurs at the same rate for all liquids and solids

13. Compare to burn due to air at 1000 C, a burn due to steam at 100°C is
(a) equally dangerous
(b) more dangerous
(c) less dangerous
(d) none of these

14. Temperature of the sun IS measured with a
(a) gas thermometer
(b) platinum thermometer
(c) Pyrometer
(d) vapour pressure thermometer

15. With a rise in boiling point of water, latent heat of steam
(a) does not change
(b) decreases
(c) increases
(d) sometimes increases and sometimes decreases

16. Ring shaped piece of metal is heated. If metal expands, hole will
(a) expand or contract depending on width of the ring
(b) expand or contract depending on width of expansion
(c) contract
(d) expand

17. Water can be made to boil at 0°C if pressure of surroundings is
(a) 0.4 mm of Hg
(b) 4 mm of Hg
(c) 40 mm of Hg
(d) 400 mm of Hg

18. Triple point of water is
(a) 273.16°C
(b) 373.16K
(c) 273.16K
(d) 273.16 F

19. Of the following thermomete1, the one which can be used for measuring a temperature of the order of 5000°C is
(a) resistance thermometer
(c) vapour pressure thermometer
(d) const. volume gas thermometer

20. While vapour condenses into liquid,
(a) its temperature increases
(b) its temperature decreases
(c) it absorbs heat
(d) it liberates heat

21. Of following gas thermometers, one which can be used for measure very low temperatures is
(a) oxygen
(b) helium
(c) hydrogen
(d) chlorine

22. Heat required to convert one gin of ice at 0°C into steam at 100°C is
(a) 516cal
(b) 616cal
(c) 716 cal
(d) 816 cal

23. While a solid is heated, the greatest % amplify takes place in its
(a) perimeter
(b) volume
(c) length
(d) area

24. The unit of heat is
(a) joule
(b) watts
(c) H.P
(d) calorie

25. A few quantity of tap water is placed in an open pan and allowed to evaporate. After Sometime the temperature of the water
(a) increases considerably
(b) remains the same
(c) increases slightly
(d) decreases slightly

26. lf pressure of the surroundings increases, then latent heat of steam
(a) remains constant
(b) increases
(c) decreases
(d) changes erratically

27. The standard fixed point for temperature amount in use today is
(a) of pure ice and pure water in equilibrium at 1 atms. pressure
(b) at which ice, liquid water and water vapour coexist
(c) melting point of ice at one atmospheric pressure
(d) none of the above

28. Paraffin wax contracts on solidification. Melting point of wax will
(a) not change with pressure
(b) decrease linearly with pressure
(c) decrease with pressure
(d) increase with pressure

29. Newly, the phenomenon of super conductivity has been experiential at 95°K. This temperature is almost equal to
(a) -40°F
(b) -288°F
(c) -288°C
(d) -373°C

30. Of following substance, one which has no melting point is
(a) CO2
(b) Al
(c) Hg
(d) Glass

31. Newton’s law of cooling is use in laboratory for purpose of
(a) specific heat of liquids
(b) latent heat of liquids
(c) latent heat of gases
(d) specific heat of gases

32. Fan produces a feeling of ease during hot weather as
(a) the fan cools the air
(b) a fan supplies hot air
(c) conductivity of air increases
(d) our perspiration evaporates rapidly

33. If bimetallic strip is heated it will
(a) not bend at all
(b) twist itself into a helix
(c) bend towards the metal with a higher thermal expansion coefficient
(d) bend towards the metal with lower thermal expansion coefficient

34. Boyle’s law holds good for an ideal gas during an
(b) isobaric change
(c) isothermal change
(d) isotopic change

35. Two spheres of similar radius are prepared from same material. One is hollow and other is solid. If they are heated as of 20°C to 100°C,
(a) the hollow spheres will expand more
(b) the solid sphere will expand more
(c) both spheres will expand equally
(d) expansion varies from material to material

36. On a exacting day, the relative humidity is 100% and room temperature is 30°C, then dew point is
(a) 15°C
(b) 30°C
(c) 45°C
(d) 60°C

37. High difference among wet bulb and dry bulb indicates
(a) higher dew point
(b) higher relative humidity
(c) lower relative humidity
(d) nothing can be said about relative humidity

38. Hygrometer is an instrument use for measuring
(a) the density of air
(b) the water vapour in the atmosphere
(c) expansion of water vapour with temperature
(d) the amount of O2 in air

39. Amount of heat necessary to raise temperature of 1 kg of water by 10°C is called
(a) Calorie
(b) K-calorie
(c) B.Th.U
(d) Cal/°C

40. Beaker of water is placed on a table. It can be prepared to boil by passing
(a) a hot wire through it
(b) steam through it at atmospheric pressure
(c) steam through it at a pressure lower than the atmospheric pressure
(d) steam through it at a pressure higher than the atmospheric pressure

41. 80 gm of water at 30°C is poured on a large block of ice at 0°C. Mass of ice that melt is
(a) 15gm
(b) 30gm
(c) 45 gm
(d) 60 gm

42. Internal energy of a gram-molecule of an ideal gas depends on
(a) temperature alone
(b) volume alone
(c) pressure alone
(d) pressure as well as temperature

43. Body in a room cools from 85°C to 80°C in 5 minutes. Time taken to cool as of 80°C to 75°C is
(a) 5 mts
(b) > 5 mts
(c) <5 mts
(d) >< 5 mts depending on the nature of the body

44. While a soluble impurity is added to a liquid, freezing point of liquid
(a) decreases
(b) increases (c) remains stationary
(d) may rise or fall.

45. If liter of an ideal gas at 27°C is heated at a steady pressure to 297°C, then final volume roughly
(a) 1.0 litres
(b) 1.9 litres
(c) 2.1 litres
(d) 32 litres

46. Two blocks of ice as pressed, pin to type one block as
(a) melting point of ice increases with increase in pressure
(b) melting point of ice decreases with increase in pressure
(c) of cold produced during pressure
(d) of heat produced during pressing

47. Large iceberg melts at base but not at top because
(a) the ice at the top is of a different kind
(b) the ice at the base contains impurities
(c) the base of an iceberg remains in warmer conditions
(d) the high pressure ice at the base lowers its melting point

48. If critical temperature of a gas is 100°C, its Boyle temperature will be approximately
(a) 500°C
(b) 1000°C
(c) 1500°C
(d) 2000°C

49. In an isothermal process, there is no change in
(a) pressure
(b) work done
(c) internal energy
(d) temperature

50. Temperature under which a gas should be cooled before it can be liquified by pressure only is
termed as
(a) the freezing point
(b) the saturation point
(c) the dew point
(d) the critical point

51. Curve drawn among 2 points on a P-V diagram represents
(a) work done in a cyclic process
(b) work done on or by the system
(c) the state of a system
(d) a thermodynamic process

52. Pressure exerted through a perfect gas is equal to
(a) 1/3 mean K.E./ volume
(b) 1/2 mean K.E./ volume
(c) 2/3 mean K.E./ volume
(d) mean K.E./volume

53. No dew is formed on a gusty night because
(a) the sky is not clear
(b) the temperature remains high
(c) there is less moisture in the air
(d) the rate of evaporation is rapid

54. In an adiabatic method there is no
(a) work done
(b) exchange of heat
(c) change in temperature
(d) change in internal energy

55. Thermodynamics generally deals with
(a) conversion of heat into other forms of energy
(b) change of state
(c) transfer of quantity of heat
(d) measurement of quantity of heat

56. Relative humidity cannot be
(a) 20%
(b) 50%
(c) 100%
(d) > 100%

57. Pressure exerted on walls of a container through a gas is due to fact that gas molecules are
(a) sticking to the walls
(b) losing their kinetic energy
(c) changing their moment a due to collision with the walls
(d) getting accelerated towards the wall

58. In an isochoric change, there is no
(a) change in pressure
(b) change in volume
(c) change in work done or volume
(d) change in temperature only

59. Internal energy of a monatomic ideal gas molecule is
(a) potential
(b) kinetic
(c) partially potential and partially kinetic
(d) neither kinetic nor potential

60. On basis of kinetic theory of gases, absolute zero Is that temperature at which molecules of a gas
(a) will start emitting light
(b) will come to a standstill
(c) will becomes massless
(d) will Shrink to points

61. In an isobaric change, there is no
(a) exchange of heat
(b) change in volume
(c) change in pressure
(d) change in temperature

62. Work done in isothermal expansion of a gas depends upon
(a) both the temperature and the expansion ratio
(b) neither the temperature nor the expansion ratio
(c) the expansion ratio only
(d) the temperature only

63. Temperature at which the r.m.s. velocity of oxygen molecules equals that of nitrogen molecules at 100°C is nearly
(a) 4.263 K
(b) 42.63K
(c) 426.3K
(d) 4263K

64. 2nd law of thermodynamics implies
(a) that a refrigerator can reduce temperature to absolute zero
(a) that every heat engine has an efficiency of 100%
(c) that all the heat can be converted to mechanical energy
(d) that no heat engine can have an efficiency of 100%

65. Specific heat of an ideal gas is
(a) inversely proportional to T
(b) proportional to T
(c) proportional to T2
(d) independent of T

66. For a gas r.m.s speed at 800°K is
(a) the same as at 20°K
(b) twice the value at 20°K
(c) half the value at 20°K
(d) 4 times the value at 20°K

67. There is no atmosphere on moon because,
(a) there is vacuum in space
(b) the diffusion coefficient of gases is large
(c) the escape velocity on the surface is low
(d) no vegetation is present

68. Area inside a closed curve on a P-V diagram represents
(a) work done in a cyclic process
(b) work done on or by the system
(c) the conditions of a system
(d) a thermodynamic process

69. 1st law of thermodynamics is concerned by conservation of
(a) the number of molecules
(b) temperature
(C) energy
(d) number of molecules

70. Difference among molar specific heats of a gas at constant pressure and at constant volume is equal to
(a) Gas constant
(b) Boltzmann’s constant
(c) Stefan’s constant
(d) Rydberg’s constant

71. Work done in adiabatic change in a particular gas depends simply upon
(a) change in temperature
(b) change in pressure
(c) change in volume
(d) norm of the above

72. Spectrum from a black body radiation is a
(a) band spectrum
(b) line spectrum
(c) continous spectrum
(d) line and band spectrum

73. If a gas at NTP is slowly compressed to 1/4 of its original volume, then the final pressure is
(a) 2 atmosphere
(b) 4 atmosphere
(c) 6 atmosphere
(d) I atmosphere

74. In adiabatic expansion of a gas, the product of pressure and volume
(a) changes erratically
(b) remains constant
(c) decreases
(d) increases

75. A refrigerator is
(a) an air cooler
(b) an electric motor
(c) a heat engine
(d) a heat engine working backwards

76. Through opening the door of a refrigerator which is inside a room,
(a) you can cool or warm the room
(b) you can neither cool nor warm the room
(c) you ultimately warm the room slightly
(d) you can cool the room to a certain degree

77. It is hotter for same distance over top of the fire than it is on the side mostly because