{"id":15888,"date":"2025-11-06T07:34:22","date_gmt":"2025-11-06T07:34:22","guid":{"rendered":"https:\/\/mcqsadda.com\/?p=15888"},"modified":"2025-11-06T08:43:04","modified_gmt":"2025-11-06T08:43:04","slug":"heat-top-100-mcqs-with-answer-and-explanation-2","status":"publish","type":"post","link":"https:\/\/mcqsadda.com\/index.php\/2025\/11\/06\/heat-top-100-mcqs-with-answer-and-explanation-2\/","title":{"rendered":"Heat Top 100 MCQs With Answer and Explanation"},"content":{"rendered":"\n

1. Heat is a form of \u2014<\/mark><\/strong>
A) Light energy
B) Kinetic energy
C) Potential energy
D) Electrical energy
Answer:<\/strong> B) Kinetic energy
Explanation:<\/strong> Heat is the total kinetic energy of all molecules of a substance due to their random motion.<\/p>\n\n\n\n

2. The S.I. unit of heat is \u2014<\/mark><\/strong>
A) Calorie
B) Joule
C) Kelvin
D) Erg
Answer:<\/strong> B) Joule
Explanation:<\/strong> Joule (J) is the SI unit of heat and energy. 1 calorie = 4.186 J.<\/p>\n\n\n\n

3. The device used to measure temperature is \u2014<\/mark><\/strong>
A) Barometer
B) Thermometer
C) Hygrometer
D) Pyrometer
Answer:<\/strong> B) Thermometer
Explanation:<\/strong> Thermometers are used to measure temperature.<\/p>\n\n\n\n

4. The S.I. unit of temperature is \u2014<\/mark><\/strong>
A) Celsius
B) Fahrenheit
C) Kelvin
D) Centigrade
Answer:<\/strong> C) Kelvin
Explanation:<\/strong> Kelvin (K) is the SI unit of thermodynamic temperature.<\/p>\n\n\n\n

5. The normal temperature of the human body is \u2014<\/mark><\/strong>
A) 98.4\u00b0F
B) 96.8\u00b0F
C) 100\u00b0F
D) 99\u00b0F
Answer:<\/strong> A) 98.4\u00b0F
Explanation:<\/strong> Normal body temperature is 37\u00b0C or 98.4\u00b0F.<\/p>\n\n\n\n

6. The temperature at which a solid changes into liquid is called \u2014<\/mark><\/strong>
A) Boiling point
B) Melting point
C) Evaporation point
D) Condensation point
Answer:<\/strong> B) Melting point
Explanation:<\/strong> Melting point is the temperature at which solid becomes liquid.<\/p>\n\n\n\n

7. The temperature at which liquid changes into gas is called \u2014<\/mark><\/strong>
A) Melting point
B) Freezing point
C) Boiling point
D) Evaporation point
Answer:<\/strong> C) Boiling point
Explanation:<\/strong> Boiling point is the temperature at which vaporization occurs.<\/p>\n\n\n\n

8. The freezing point of water is \u2014<\/mark><\/strong>
A) 0\u00b0C
B) 32\u00b0C
C) 100\u00b0C
D) 273 K
Answer:<\/strong> A) 0\u00b0C
Explanation:<\/strong> Water freezes at 0\u00b0C or 273 K.<\/p>\n\n\n\n

9. The boiling point of water is \u2014<\/mark><\/strong>
A) 50\u00b0C
B) 90\u00b0C
C) 100\u00b0C
D) 120\u00b0C
Answer:<\/strong> C) 100\u00b0C
Explanation:<\/strong> At normal pressure, water boils at 100\u00b0C or 373 K.<\/p>\n\n\n\n

10. The heat required to raise the temperature of 1 kg of a substance by 1\u00b0C is called \u2014<\/mark><\/strong>
A) Latent heat
B) Specific heat
C) Heat capacity
D) Thermal energy
Answer:<\/strong> B) Specific heat
Explanation:<\/strong> Specific heat (c) = Heat \/ (mass \u00d7 temperature change).<\/p>\n\n\n\n

11. The S.I. unit of specific heat is \u2014<\/mark><\/strong>
A) J\/kg
B) J\/kg\u00b0C
C) J\/\u00b0C
D) J\/m\u00b2
Answer:<\/strong> B) J\/kg\u00b0C
Explanation:<\/strong> Unit = joules per kilogram per degree Celsius.<\/p>\n\n\n\n

12. The heat required to change the state of a substance without change in temperature is called \u2014<\/mark><\/strong>
A) Latent heat
B) Sensible heat
C) Specific heat
D) Potential energy
Answer:<\/strong> A) Latent heat
Explanation:<\/strong> Latent heat changes state but not temperature.<\/p>\n\n\n\n

13. The S.I. unit of latent heat is \u2014<\/mark><\/strong>
A) J\/kg
B) J\/mol
C) Cal\/g
D) KJ\/kg
Answer:<\/strong> A) J\/kg
Explanation:<\/strong> It is measured as energy per unit mass.<\/p>\n\n\n\n

14. Heat always flows from \u2014<\/mark><\/strong>
A) Cold to hot
B) Hot to cold
C) Lower to higher potential
D) None
Answer:<\/strong> B) Hot to cold
Explanation:<\/strong> Heat naturally flows from higher temperature to lower temperature.<\/p>\n\n\n\n

15. The process by which heat is transferred without actual movement of particles is \u2014
<\/mark><\/strong>A) Conduction
B) Convection
C) Radiation
D) Evaporation
Answer:<\/strong> C) Radiation
Explanation:<\/strong> In radiation, heat travels through vacuum by electromagnetic waves.<\/p>\n\n\n\n

16.<\/strong> Conduction takes place mainly in \u2014
A) Solids
B) Liquids
C) Gases
D) Vacuum
Answer:<\/strong> A) Solids
Explanation:<\/strong> Solids conduct heat because their particles are closely packed.<\/p>\n\n\n\n

17. Convection takes place mainly in \u2014<\/mark><\/strong>
A) Solids
B) Liquids and gases
C) Metals
D) Vacuum
Answer:<\/strong> B) Liquids and gases
Explanation:<\/strong> Convection is due to movement of particles, which occurs in fluids.<\/p>\n\n\n\n

18. Heat transfer by radiation requires \u2014<\/mark><\/strong>
A) Medium
B) Air
C) Solid contact
D) No medium
Answer:<\/strong> D) No medium
Explanation:<\/strong> Radiation can occur even in vacuum, e.g., heat from the Sun.<\/p>\n\n\n\n

19. A good conductor of heat is \u2014<\/mark><\/strong>
A) Copper
B) Wood
C) Plastic
D) Rubber
Answer:<\/strong> A) Copper
Explanation:<\/strong> Metals like copper and aluminum are good conductors.<\/p>\n\n\n\n

20. A bad conductor of heat is \u2014<\/mark><\/strong>
A) Iron
B) Aluminum
C) Glass
D) Silver
Answer:<\/strong> C) Glass
Explanation:<\/strong> Glass is a poor conductor and used in thermos flasks to prevent heat loss.<\/p>\n\n\n\n

21. The best conductor of heat among the following is \u2014<\/mark><\/strong>
A) Copper
B) Silver
C) Iron
D) Aluminium
Answer:<\/strong> B) Silver
Explanation:<\/strong> Silver is the best conductor of heat and electricity among metals.<\/p>\n\n\n\n

22. The poorest conductor of heat among the following is \u2014<\/mark><\/strong>
A) Rubber
B) Water
C) Air
D) Wood
Answer:<\/strong> C) Air
Explanation:<\/strong> Air has very low thermal conductivity and acts as an insulator.<\/p>\n\n\n\n

23. The process by which heat is transferred in solids is \u2014<\/mark><\/strong>
A) Conduction
B) Convection
C) Radiation
D) Diffusion
Answer:<\/strong> A) Conduction
Explanation:<\/strong> In solids, heat is transferred through molecular vibrations.<\/p>\n\n\n\n

24. The process by which heat is transferred in liquids and gases is \u2014<\/mark><\/strong>
A) Conduction
B) Convection
C) Radiation
D) Diffusion
Answer:<\/strong> B) Convection
Explanation:<\/strong> Heat transfer occurs through actual movement of fluid molecules.<\/p>\n\n\n\n

25. The process by which heat is transferred from the Sun to the Earth is \u2014
<\/mark><\/strong>A) Conduction
B) Convection
C) Radiation
D) Reflection
Answer:<\/strong> C) Radiation
Explanation:<\/strong> Radiation can travel through vacuum \u2014 no medium required.<\/p>\n\n\n\n

26. Which of the following surfaces is a good absorber of heat?
<\/mark><\/strong>A) Shiny and white
B) Smooth and silver
C) Rough and black
D) Polished and bright
Answer:<\/strong> C) Rough and black
Explanation:<\/strong> Dark, rough surfaces absorb more heat radiation.<\/p>\n\n\n\n

27. A good absorber of heat is also a good \u2014
<\/mark><\/strong>A) Reflector
B) Radiator (emitter)
C) Conductor
D) Insulator
Answer:<\/strong> B) Radiator (emitter)
Explanation:<\/strong> According to Kirchhoff\u2019s law, good absorbers are good emitters.<\/p>\n\n\n\n

28. In a thermos flask, heat transfer is minimized by \u2014
<\/mark><\/strong>A) Conduction only
B) Convection only
C) Radiation only
D) All three methods
Answer:<\/strong> D) All three methods
Explanation:<\/strong> Thermos prevents heat loss by conduction, convection, and radiation.<\/p>\n\n\n\n

29. The fixed points of a thermometer are \u2014
<\/mark><\/strong>A) Freezing and boiling points of water
B) Room and body temperature
C) Boiling point and melting point of mercury
D) Ice point and steam point
Answer:<\/strong> A) Freezing and boiling points of water
Explanation:<\/strong> These two fixed points are used to calibrate thermometers.<\/p>\n\n\n\n

30. Temperature is a measure of \u2014
<\/mark><\/strong>A) Total heat energy
B) Average kinetic energy of particles
C) Potential energy
D) Internal energy
Answer:<\/strong> B) Average kinetic energy of particles
Explanation:<\/strong> Temperature measures how fast particles move on average.<\/p>\n\n\n\n

31. Which of the following has the highest specific heat?<\/mark><\/strong>
A) Water
B) Mercury
C) Iron
D) Copper
Answer:<\/strong> A) Water
Explanation:<\/strong> Water has very high specific heat (4200 J\/kg\u00b0C), making it an excellent coolant.<\/p>\n\n\n\n

32. A device used to measure high temperatures (e.g., in furnaces) is \u2014
<\/mark><\/strong>A) Clinical thermometer
B) Laboratory thermometer
C) Pyrometer
D) Manometer
Answer:<\/strong> C) Pyrometer
Explanation:<\/strong> Pyrometers measure very high temperatures without contact.<\/p>\n\n\n\n

33. The specific heat of a substance depends on \u2014<\/mark><\/strong>
A) Nature of material
B) Shape of material
C) Color of material
D) Size of material
Answer:<\/strong> A) Nature of material
Explanation:<\/strong> Different materials store heat energy differently due to molecular structure.<\/p>\n\n\n\n

34. The amount of heat required to change 1 kg of ice into water at 0\u00b0C without change of temperature is called \u2014
<\/mark><\/strong>A) Latent heat of vaporization
B) Latent heat of fusion
C) Specific heat
D) Thermal capacity
Answer:<\/strong> B) Latent heat of fusion
Explanation:<\/strong> It\u2019s the heat needed to melt solid \u2192 liquid at constant temperature.<\/p>\n\n\n\n

35. The amount of heat required to change 1 kg of water into vapor at 100\u00b0C without temperature change is \u2014<\/mark><\/strong>
A) Latent heat of fusion
B) Latent heat of vaporization
C) Specific heat
D) Melting heat
Answer:<\/strong> B) Latent heat of vaporization
Explanation:<\/strong> It\u2019s the energy needed for phase change from liquid to vapor.<\/p>\n\n\n\n

36. The S.I. unit of heat capacity is \u2014<\/mark><\/strong>
A) Joule
B) J\/kg\u00b0C
C) J\/\u00b0C
D) Calorie
Answer:<\/strong> C) J\/\u00b0C
Explanation:<\/strong> Heat capacity = Heat \/ Temperature change \u2192 joules per degree.<\/p>\n\n\n\n

37. When ice melts into water, heat energy \u2014<\/strong>
<\/mark>A) Increases temperature
B) Decreases temperature
C) Changes state only
D) Is lost completely
Answer:<\/strong> C) Changes state only
Explanation:<\/strong> During melting, temperature remains constant \u2014 heat used for state change.<\/p>\n\n\n\n

38. When water boils, the temperature \u2014<\/mark><\/strong>
A) Increases continuously
B) Decreases gradually
C) Remains constant
D) Becomes zero
Answer:<\/strong> C) Remains constant
Explanation:<\/strong> During boiling, heat is used to convert liquid \u2192 vapor (latent heat).<\/p>\n\n\n\n

39. Expansion of a substance on heating is due to \u2014<\/mark><\/strong>
A) Decrease in molecular distance
B) Increase in molecular distance
C) Chemical reaction
D) Change in density
Answer:<\/strong> B) Increase in molecular distance
Explanation:<\/strong> On heating, molecules vibrate more and move farther apart.<\/p>\n\n\n\n

40. The increase in length of a solid when heated is called \u2014<\/mark><\/strong>
A) Cubical expansion
B) Linear expansion
C) Superficial expansion
D) Thermal expansion
Answer:<\/strong> B) Linear expansion
Explanation:<\/strong> Linear expansion occurs along one dimension (length).<\/p>\n\n\n\n

41. When a metal ring is heated, the hole in the ring \u2014
<\/mark><\/strong>A) Expands
B) Contracts
C) Remains same
D) Becomes irregular
Answer:<\/strong> A) Expands
Explanation:<\/strong> On heating, every part of the ring expands; hence, even the hole increases in size.<\/p>\n\n\n\n

42. The coefficient of linear expansion is expressed in \u2014<\/mark><\/strong>
A) \u00b0C
B) m
C) m\/\u00b0C
D) per \u00b0C
Answer:<\/strong> D) per \u00b0C
Explanation:<\/strong> Coefficient of expansion = fractional change in length per \u00b0C rise in temperature.<\/p>\n\n\n\n

43. The expansion of a liquid on heating is called \u2014<\/mark><\/strong>
A) Linear expansion
B) Cubical expansion
C) Superficial expansion
D) Thermal expansion
Answer:<\/strong> B) Cubical expansion
Explanation:<\/strong> Liquids have volume expansion because they have no fixed shape.<\/p>\n\n\n\n

44. The temperature at which water has maximum density is \u2014
<\/mark><\/strong>A) 0\u00b0C
B) 4\u00b0C
C) 10\u00b0C
D) 100\u00b0C
Answer:<\/strong> B) 4\u00b0C
Explanation:<\/strong> Water is densest at 4\u00b0C; below or above this, density decreases.<\/p>\n\n\n\n

45. The process of heat transfer in which no medium is required is \u2014
<\/mark><\/strong>A) Conduction
B) Convection
C) Radiation
D) None of these
Answer:<\/strong> C) Radiation
Explanation:<\/strong> Radiation can occur even through vacuum (e.g., sunlight).<\/p>\n\n\n\n

46. The heat energy required to convert 1 g of ice at 0\u00b0C to 1 g of water at 0\u00b0C is \u2014
<\/mark><\/strong>A) 80 cal
B) 540 cal
C) 100 cal
D) 1 cal
Answer:<\/strong> A) 80 cal
Explanation:<\/strong> Latent heat of fusion of ice = 80 cal\/g.<\/p>\n\n\n\n

47. The heat energy required to convert 1 g of water at 100\u00b0C into steam at 100\u00b0C is \u2014
<\/strong><\/mark>A) 80 cal
B) 540 cal
C) 100 cal
D) 1 cal
Answer:<\/strong> B) 540 cal
Explanation:<\/strong> Latent heat of vaporization of water = 540 cal\/g.<\/p>\n\n\n\n

48. When a solid is heated, its mass \u2014<\/mark><\/strong>
A) Increases
B) Decreases
C) Remains constant
D) First increases then decreases
Answer:<\/strong> C) Remains constant
Explanation:<\/strong> Heating changes size and volume but not mass.<\/p>\n\n\n\n

49. When heat is supplied to a body, it may \u2014<\/mark><\/strong>
A) Raise temperature only
B) Change state only
C) Either raise temperature or change state
D) Reflect energy
Answer:<\/strong> C) Either raise temperature or change state
Explanation:<\/strong> Depending on the condition, heat causes temperature rise or phase change.<\/p>\n\n\n\n

50. The transfer of heat by convection in a liquid takes place due to \u2014
<\/mark><\/strong>A) Conduction of molecules
B) Radiation of molecules
C) Movement of molecules
D) Collision of molecules
Answer:<\/strong> C) Movement of molecules
Explanation:<\/strong> In convection, molecules move carrying heat energy.<\/p>\n\n\n\n

51. When water is heated from 0\u00b0C to 4\u00b0C, its volume \u2014
<\/mark><\/strong>A) Increases
B) Decreases
C) Remains constant
D) Increases then decreases
Answer:<\/strong> B) Decreases
Explanation:<\/strong> Water shows anomalous expansion \u2014 contracts till 4\u00b0C and then expands.<\/p>\n\n\n\n

52. The anomalous expansion of water is useful in \u2014
<\/mark><\/strong>A) Boiling water faster
B) Survival of aquatic life in winter
C) Increasing density of water
D) Freezing quickly
Answer:<\/strong> B) Survival of aquatic life in winter
Explanation:<\/strong> Ice floats and insulates lower water layers, allowing aquatic life to survive.<\/p>\n\n\n\n

53. The heat energy per unit mass required to change a solid into a liquid without temperature change is \u2014
<\/mark><\/strong>A) Latent heat of vaporization
B) Latent heat of fusion
C) Specific heat
D) Thermal capacity
Answer:<\/strong> B) Latent heat of fusion
Explanation:<\/strong> Fusion is solid \u2192 liquid phase change.<\/p>\n\n\n\n

54. The heat energy per unit mass required to change a liquid into vapor without temperature change is \u2014
<\/mark><\/strong>A) Latent heat of fusion
B) Latent heat of vaporization
C) Specific heat
D) Thermal capacity
Answer:<\/strong> B) Latent heat of vaporization
Explanation:<\/strong> It measures heat required for liquid \u2192 vapor.<\/p>\n\n\n\n

55. The process of cooling due to evaporation takes place because \u2014
<\/mark><\/strong>A) All molecules escape
B) The faster molecules leave, reducing average kinetic energy
C) Molecules gain energy from surroundings
D) Temperature increases
Answer:<\/strong> B) The faster molecules leave, reducing average kinetic energy
Explanation:<\/strong> Evaporation removes high-energy molecules \u2192 cooling effect.<\/p>\n\n\n\n

56. When you feel cool after applying alcohol on skin, it is due to \u2014
<\/mark><\/strong>A) Boiling
B) Radiation
C) Evaporation
D) Condensation
Answer:<\/strong> C) Evaporation
Explanation:<\/strong> Alcohol evaporates quickly, taking away heat from the skin.<\/p>\n\n\n\n

57. The boiling point of water decreases when \u2014
<\/mark><\/strong>A) Pressure increases
B) Pressure decreases
C) Temperature increases
D) Impurities increase
Answer:<\/strong> B) Pressure decreases
Explanation:<\/strong> At higher altitudes (low pressure), water boils at lower temperatures.<\/p>\n\n\n\n

58. When vapor changes into liquid, the process is called \u2014
<\/mark><\/strong>A) Fusion
B) Condensation
C) Evaporation
D) Boiling
Answer:<\/strong> B) Condensation
Explanation:<\/strong> Conversion of gas to liquid by releasing heat energy.<\/p>\n\n\n\n

59. The boiling point of water increases when \u2014
<\/mark><\/strong>A) Pressure increases
B) Pressure decreases
C) Temperature decreases
D) Air is removed
Answer:<\/strong> A) Pressure increases
Explanation:<\/strong> More pressure means molecules need higher energy to escape.<\/p>\n\n\n\n

60. The process of heat transfer that takes place between Earth and Sun is \u2014
<\/mark><\/strong>A) Conduction
B) Convection
C) Radiation
D) Reflection
Answer:<\/strong> C) Radiation
Explanation:<\/strong> Heat from the Sun reaches Earth through vacuum via radiation.<\/p>\n\n\n\n

61. The transfer of heat by molecular collision is called \u2014
<\/mark><\/strong>A) Conduction
B) Convection
C) Radiation
D) Reflection
Answer:<\/strong> A) Conduction
Explanation:<\/strong> In conduction, energy is passed from one molecule to another by vibration and collision.<\/p>\n\n\n\n

62. The metallic rod feels colder than a wooden rod at the same temperature because \u2014
<\/mark><\/strong>A) Metal expands more
B) Metal conducts heat faster
C) Metal is heavier
D) Wood absorbs moisture
Answer:<\/strong> B) Metal conducts heat faster
Explanation:<\/strong> Metal quickly draws heat away from the hand due to high thermal conductivity.<\/p>\n\n\n\n

63. Heat energy absorbed or released during change of state is called \u2014
<\/mark><\/strong>A) Sensible heat
B) Latent heat
C) Specific heat
D) Thermal energy
Answer:<\/strong> B) Latent heat
Explanation:<\/strong> Latent heat changes phase without temperature change.<\/p>\n\n\n\n

64. The phenomenon of sea breeze is due to \u2014
<\/mark><\/strong>A) Conduction
B) Convection
C) Radiation
D) Reflection
Answer:<\/strong> B) Convection
Explanation:<\/strong> During day, warm air rises from land and cool air from sea replaces it \u2014 convection current.<\/p>\n\n\n\n

65. The phenomenon of land breeze occurs \u2014
<\/mark><\/strong>A) During the day
B) During the night
C) During evening only
D) In deserts only
Answer:<\/strong> B) During the night
Explanation:<\/strong> At night, land cools faster than sea \u2014 air moves from land to sea.<\/p>\n\n\n\n

66. The process by which heat is transferred in liquids and gases due to actual movement of particles is \u2014
<\/mark><\/strong>A) Conduction
B) Convection
C) Radiation
D) Reflection
Answer:<\/strong> B) Convection
Explanation:<\/strong> Fluids transfer heat by movement of warmer and cooler parts.<\/p>\n\n\n\n

67. The device which minimizes heat loss due to conduction, convection, and radiation is \u2014
<\/mark><\/strong>A) Radiator
B) Thermos flask
C) Refrigerator
D) Solar cooker
Answer:<\/strong> B) Thermos flask
Explanation:<\/strong> Vacuum and reflective walls prevent all three modes of heat transfer.<\/p>\n\n\n\n

68. On a hot day, a person wearing white clothes feels cooler because \u2014
<\/mark><\/strong>A) White color absorbs all heat
B) White color reflects most of the heat
C) White color emits heat
D) White color absorbs sunlight
Answer:<\/strong> B) White color reflects most of the heat
Explanation:<\/strong> Light-colored clothes reflect heat and keep the body cool.<\/p>\n\n\n\n

69. The heat required to raise the temperature of a body by 1\u00b0C is called \u2014
<\/mark><\/strong>A) Specific heat
B) Latent heat
C) Thermal capacity
D) Heat energy
Answer:<\/strong> C) Thermal capacity
Explanation:<\/strong> Thermal capacity = Heat required \/ temperature change = m \u00d7 c.<\/p>\n\n\n\n

70. When ice at 0\u00b0C melts to water at 0\u00b0C, heat absorbed is \u2014
<\/mark><\/strong>A) Latent heat
B) Specific heat
C) Sensible heat
D) Conduction heat
Answer:<\/strong> A) Latent heat
Explanation:<\/strong> Heat changes phase (solid \u2192 liquid) without temperature rise.<\/p>\n\n\n\n

71. When vapor converts into liquid, it \u2014
<\/mark><\/strong>A) Absorbs heat
B) Releases heat
C) Does not change energy
D) Cools rapidly
Answer:<\/strong> B) Releases heat
Explanation:<\/strong> Condensation releases latent heat to surroundings.<\/p>\n\n\n\n

72. Frost forms on cold surfaces due to \u2014
<\/mark><\/strong>A) Evaporation
B) Sublimation
C) Condensation
D) Freezing
Answer:<\/strong> B) Sublimation
Explanation:<\/strong> Water vapor directly changes to ice without becoming liquid.<\/p>\n\n\n\n

73. Boiling occurs when \u2014
<\/mark><\/strong>A) Temperature decreases
B) Vapour pressure equals external pressure
C) Vapour pressure becomes less than atmospheric pressure
D) Vapour pressure becomes zero
Answer:<\/strong> B) Vapour pressure equals external pressure
Explanation:<\/strong> Boiling begins when internal vapor pressure matches external pressure.<\/p>\n\n\n\n

74. Evaporation of water is faster when \u2014
<\/mark><\/strong>A) Temperature is low
B) Air is still
C) Humidity is low
D) Surface area is small
Answer:<\/strong> C) Humidity is low
Explanation:<\/strong> Dry air allows faster evaporation since it can hold more vapor.<\/p>\n\n\n\n

75. Which of the following factors does not affect evaporation?
<\/mark><\/strong>A) Surface area
B) Temperature
C) Humidity
D) Density of liquid
Answer:<\/strong> D) Density of liquid
Explanation:<\/strong> Evaporation depends mainly on surface area, temperature, and humidity.<\/p>\n\n\n\n

76. The freezing point of water in Kelvin scale is \u2014
<\/mark><\/strong>A) 100 K
B) 273 K
C) 373 K
D) 273\u00b0C
Answer:<\/strong> B) 273 K
Explanation:<\/strong> 0\u00b0C=273\u2009K0\u00b0C = 273 \\, K0\u00b0C=273K<\/p>\n\n\n\n

77. The boiling point of water in Kelvin scale is \u2014
<\/mark><\/strong>A) 273 K
B) 300 K
C) 373 K
D) 400 K
Answer:<\/strong> C) 373 K
Explanation:<\/strong> 100\u00b0C=373\u2009K100\u00b0C = 373 \\, K100\u00b0C=373K<\/p>\n\n\n\n

78. Which law states that heat lost by hot body equals heat gained by cold body in an isolated system?
<\/mark><\/strong>A) Joule\u2019s Law
B) Law of Cooling
C) Principle of Calorimetry
D) Newton\u2019s Law
Answer:<\/strong> C) Principle of Calorimetry
Explanation:<\/strong> Qlost=QgainedQ_{\\text{lost}} = Q_{\\text{gained}}Qlost\u200b=Qgained\u200b \u2014 conservation of energy.<\/p>\n\n\n\n

79. The instrument used to measure specific heat capacity is \u2014
<\/mark><\/strong>A) Thermometer
B) Calorimeter
C) Manometer
D) Hygrometer
Answer:<\/strong> B) Calorimeter
Explanation:<\/strong> Calorimeter measures heat exchange between substances.<\/p>\n\n\n\n

80. The process in which heat is transferred from one part of a body to another without movement of particles is \u2014
<\/mark><\/strong>A) Convection
B) Conduction
C) Radiation
D) Reflection
Answer:<\/strong> B) Conduction
Explanation:<\/strong> In solids, heat passes by vibration of particles without actual movement.<\/p>\n\n\n\n

81. When a body cools, it \u2014
<\/mark><\/strong>A) Gains heat
B) Loses heat
C) Maintains temperature
D) Expands
Answer:<\/strong> B) Loses heat
Explanation:<\/strong> Cooling occurs due to loss of internal energy or heat to surroundings.<\/p>\n\n\n\n

82. A liquid thermometer works on the principle of \u2014
<\/mark><\/strong>A) Thermal expansion
B) Convection
C) Conduction
D) Radiation
Answer:<\/strong> A) Thermal expansion
Explanation:<\/strong> Liquids like mercury expand when heated, and the expansion indicates temperature.<\/p>\n\n\n\n

83. In thermodynamics, the measure of disorder or randomness is called \u2014
<\/mark><\/strong>A) Energy
B) Entropy
C) Pressure
D) Heat
Answer:<\/strong> B) Entropy
Explanation:<\/strong> Entropy measures the degree of disorder in a system.<\/p>\n\n\n\n

84. The heat required to raise the temperature of 1 g of water by 1\u00b0C is \u2014
<\/mark><\/strong>A) 1 cal
B) 4.2 cal
C) 10 cal
D) 0.1 cal
Answer:<\/strong> A) 1 cal
Explanation:<\/strong> By definition, 1 calorie = heat needed to raise 1 g of water by 1\u00b0C.<\/p>\n\n\n\n

85. The specific heat capacity of water is \u2014
<\/mark><\/strong>A) 420 J\/kg\u00b0C
B) 4200 J\/kg\u00b0C
C) 100 J\/kg\u00b0C
D) 4.2 J\/kg\u00b0C
Answer:<\/strong> B) 4200 J\/kg\u00b0C
Explanation:<\/strong> Water has a high specific heat of 4200 J\/kg\u00b0C, making it an effective coolant.<\/p>\n\n\n\n

86. A black body is a \u2014
<\/mark><\/strong>A) Perfect absorber and perfect emitter of heat
B) Perfect reflector
C) Perfect insulator
D) Partial absorber
Answer:<\/strong> A) Perfect absorber and perfect emitter of heat
Explanation:<\/strong> A black body absorbs all incident radiation and emits maximum possible energy.<\/p>\n\n\n\n

87. Which of the following surfaces is the best emitter of heat?<\/mark><\/strong>
A) Polished white surface
B) Rough black surface
C) Smooth silver surface
D) Mirror surface
Answer:<\/strong> B) Rough black surface
Explanation:<\/strong> Black, rough surfaces are best absorbers and emitters of radiation.<\/p>\n\n\n\n

88. The unit of heat energy commonly used in food energy is \u2014
<\/mark><\/strong>A) Calorie
B) Joule
C) Kilocalorie
D) Kelvin
Answer:<\/strong> C) Kilocalorie
Explanation:<\/strong> 1 kilocalorie = 1000 calories; used to measure energy in food.<\/p>\n\n\n\n

89. Which of the following has the lowest thermal conductivity?<\/mark><\/strong>
A) Iron
B) Wood
C) Silver
D) Aluminium
Answer:<\/strong> B) Wood
Explanation:<\/strong> Wood is an insulator and does not allow easy transfer of heat.<\/p>\n\n\n\n

90. Which gas is a poor conductor of heat and is used in thermos flasks?
<\/mark><\/strong>A) Oxygen
B) Nitrogen
C) Hydrogen
D) Carbon dioxide
Answer:<\/strong> B) Nitrogen
Explanation:<\/strong> Nitrogen is used because it has low thermal conductivity and prevents oxidation.<\/p>\n\n\n\n

91. The relationship between heat (Q), mass (m), specific heat (c), and temperature difference (\u0394T) is \u2014<\/mark><\/strong>
A) Q = mc\/\u0394T
B) Q = m + c + \u0394T
C) Q = mc\u0394T
D) Q = m\/c\u0394T
Answer:<\/strong> C) Q = mc\u0394T
Explanation:<\/strong> Formula for heat exchange when temperature changes.<\/p>\n\n\n\n

92. Which of the following is a temperature scale with absolute zero?
<\/mark><\/strong>A) Celsius
B) Fahrenheit
C) Kelvin
D) Centigrade
Answer:<\/strong> C) Kelvin
Explanation:<\/strong> Absolute zero (0 K) is the temperature at which molecular motion stops.<\/p>\n\n\n\n

93. Absolute zero temperature is \u2014
<\/mark><\/strong>A) 0\u00b0C
B) \u2212100\u00b0C
C) \u2212273\u00b0C
D) \u2212373\u00b0C
Answer:<\/strong> C) \u2212273\u00b0C
Explanation:<\/strong> \u2212273.15\u00b0C = 0 K, the lowest possible temperature.<\/p>\n\n\n\n

94. The material used for making electrical heating elements is \u2014
<\/mark><\/strong>A) Copper
B) Aluminium
C) Nichrome
D) Iron
Answer:<\/strong> C) Nichrome
Explanation:<\/strong> Nichrome has high resistivity and withstands high temperature, making it ideal for heaters.<\/p>\n\n\n\n

95. Which law states that \u201cthe rate of heat loss of a body is directly proportional to the difference in temperature between the body and its surroundings\u201d?
<\/mark><\/strong>A) Stefan\u2019s Law
B) Newton\u2019s Law of Cooling
C) Wien\u2019s Law
D) Kirchhoff\u2019s Law
Answer:<\/strong> B) Newton\u2019s Law of Cooling
Explanation:<\/strong> It applies to bodies cooling by radiation or convection.<\/p>\n\n\n\n

96. When water is boiled, bubbles appear because \u2014
<\/mark><\/strong>A) Air dissolved in water escapes
B) Water starts evaporating
C) Vapor pressure increases
D) All the above
Answer:<\/strong> D) All the above
Explanation:<\/strong> Boiling causes vapor formation and air release due to heat energy.<\/p>\n\n\n\n

97. The freezing point of seawater is \u2014
<\/mark><\/strong>A) 0\u00b0C
B) \u22122\u00b0C
C) 5\u00b0C
D) \u221210\u00b0C
Answer:<\/strong> B) \u22122\u00b0C
Explanation:<\/strong> Due to dissolved salts, seawater freezes below 0\u00b0C.<\/p>\n\n\n\n

98. The process of changing directly from solid to gas is called \u2014
<\/mark><\/strong>A) Melting
B) Sublimation
C) Evaporation
D) Condensation
Answer:<\/strong> B) Sublimation
Explanation:<\/strong> Examples include camphor and dry ice, which sublimate directly.<\/p>\n\n\n\n

99. When ice melts into water, energy \u2014
<\/mark><\/strong>A) Is absorbed
B) Is released
C) Remains constant
D) Becomes kinetic
Answer:<\/strong> A) Is absorbed
Explanation:<\/strong> Heat is absorbed (latent heat of fusion) to overcome molecular bonds.<\/p>\n\n\n\n

100. Which of the following is used in refrigerators as a cooling agent?
<\/mark><\/strong>A) Oxygen
B) Ammonia
C) Carbon dioxide
D) Nitrogen
Answer:<\/strong> B) Ammonia
Explanation:<\/strong> Ammonia is commonly used as a refrigerant due to its high latent heat of vaporization.<\/p>\n","protected":false},"excerpt":{"rendered":"

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