41. What is the SI unit of heat?
A. Calorie
B. Watt
C. Joule
D. Kelvin
Explanation: Joule is the SI unit used to measure heat energy.
42. Heat always flows from:
A. Cold body to hot body
B. Hot body to cold body
C. Lower pressure to higher pressure
D. Equal temperature bodies
Explanation: Heat naturally transfers from hotter to colder objects.
43. Which of the following is a good conductor of heat?
A. Wood
B. Plastic
C. Copper
D. Rubber
Explanation: Copper is a metal and an excellent conductor of heat.
44. What method of heat transfer occurs in solids?
A. Conduction
B. Convection
C. Radiation
D. Diffusion
Explanation: In solids, heat is transferred mainly through conduction.
45. Which physical property increases with the gain of heat?
A. Mass
B. Density
C. Pressure
D. Temperature
Explanation: When heat is added, the temperature of a substance rises.
46. Which method of heat transfer does not require a medium?
A. Conduction
B. Convection
C. Radiation
D. Diffusion
Explanation: Radiation is the only form of heat transfer that does not require a medium.
47. What is the process of heat transfer in liquids and gases called?
A. Conduction
B. Convection
C. Radiation
D. Evaporation
Explanation: Convection is the heat transfer through fluids due to movement of molecules.
48. Which of the following materials is the best insulator of heat?
A. Copper
B. Aluminum
C. Iron
D. Wool
Explanation: Wool is a poor conductor and traps heat, keeping you warm.
49. Which state of matter expands the most when heated?
A. Solid
B. Liquid
C. Gas
D. Plasma
Explanation: Gases have weak intermolecular forces and expand more than solids or liquids.
50. What is the specific heat capacity of water?
A. 1.0 J/g°C
B. 4.18 J/g°C
C. 2.5 J/g°C
D. 0.5 J/g°C
Explanation: Water has a high specific heat capacity of 4.18 joules per gram per degree Celsius.
51. Why does metal feel colder than wood at the same temperature?
A. Metal conducts heat better than wood
B. Wood has higher density
C. Metal has more mass
D. Wood reflects heat
Explanation: Metal transfers heat away from your skin quickly, giving a colder sensation.
52. Which part of the flame is the hottest?
A. Outer red zone
B. Yellow zone
C. Blue zone
D. Innermost black zone
Explanation: The blue region is the hottest part of a flame due to efficient burning.
53. Which instrument is used to measure temperature?
A. Thermometer
B. Barometer
C. Hygrometer
D. Anemometer
Explanation: A thermometer is a device that measures the temperature of a system.
54. Which form of heat transfer is responsible for warming your hands near a fire?
A. Conduction
B. Convection
C. Radiation
D. Evaporation
Explanation: Heat is radiated from the fire and directly warms your body.
55. Which surface absorbs the most heat?
A. White and shiny
B. White and rough
C. Black and smooth
D. Black and rough
Explanation: A black and rough surface absorbs the maximum amount of heat radiation.
56. Which gas is commonly used in thermometers?
A. Nitrogen
B. Oxygen
C. Mercury
D. Hydrogen
Explanation: Mercury remains liquid over a wide range and expands uniformly with heat.
57. What happens to water when it reaches 100°C at sea level?
A. It boils
B. It freezes
C. It condenses
D. It sublimates
Explanation: Boiling point of water is 100°C under standard atmospheric pressure.
58. Which color reflects most of the heat radiation?
A. Black
B. Blue
C. White
D. Red
Explanation: White reflects most heat and light, keeping objects cooler.
59. What process involves heat transfer through a solid?
A. Conduction
B. Radiation
C. Convection
D. Evaporation
Explanation: Conduction is the transfer of heat through a solid material.
60. What is the boiling point of water on the Fahrenheit scale?
A. 100°F
B. 180°F
C. 212°F
D. 32°F
Explanation: Water boils at 212°F under normal atmospheric conditions.
61. Which physical property changes when a thermometer is heated?
A. Volume
B. Mass
C. Weight
D. Color
Explanation: The volume of liquid (like mercury) changes with temperature, which is used to indicate heat.
62. Which device is used in refrigerators to control heat transfer?
A. Heater
B. Radiator
C. Burner
D. Evaporator coil
Explanation: Evaporator coils in refrigerators absorb heat and help maintain a cold environment.
63. What is the melting point of ice in Kelvin?
A. 0 K
B. 100 K
C. 273 K
D. 373 K
Explanation: 0°C is equal to 273 K on the Kelvin scale, which is the melting point of ice.
64. Heat is measured in which unit?
A. Kelvin
B. Joule
C. Celsius
D. Fahrenheit
Explanation: Heat energy is quantified in joules, the SI unit of energy.
65. Which process helps in the formation of clouds?
A. Evaporation
B. Sublimation
C. Conduction
D. Melting
Explanation: Evaporation is the primary process that converts liquid water to vapor, aiding in cloud formation.
66. Why do coastal areas have a moderate climate?
A. Due to land heating quickly
B. Due to the high heat capacity of water
C. Due to cloud formation
D. Due to rainfall
Explanation: The ocean absorbs and releases heat slowly, stabilizing the coastal temperature.
67. What causes sea breeze during the day?
A. Sea heats faster than land
B. Sea is cooler at night
C. Land heats up faster than the sea
D. Water has less specific heat
Explanation: Warm air over land rises and is replaced by cooler air from the sea, creating a breeze.
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