Heat Transfer in Nature Part 3: MCQs (Q51–Q75)
📘 Chapter 7 – Heat Transfer in Nature
🔹 Part 3: Radiation (Q51–Q75)
Q51. Radiation is the transfer of heat:
A) Through solids only
B) Through liquids only
C) Without any medium
D) By conduction
✅ Answer: C) Without any medium
Explanation: Radiation does not require particles or a medium – heat from the Sun reaches Earth this way.
Q52. Which of these transfers heat by radiation?
A) Iron rod in fire
B) Water in kettle
C) Heat from the Sun
D) Hot water rising
✅ Answer: C) Heat from the Sun
Q53. Which surface absorbs maximum heat radiation?
A) Shiny white
B) Shiny silver
C) Dull black
D) Smooth glass
✅ Answer: C) Dull black
Q54. Which surface reflects most heat radiation?
A) Black rough
B) White shiny
C) Dull black
D) Brown rough
✅ Answer: B) White shiny
Q55. Which type of heat transfer is used by the Sun to warm the Earth?
A) Conduction
B) Convection
C) Radiation
D) Reflection
✅ Answer: C) Radiation
Q56. A room becomes warm near a bonfire mainly due to:
A) Conduction
B) Convection
C) Radiation
D) None
✅ Answer: C) Radiation
Q57. Which is the fastest mode of heat transfer?
A) Conduction
B) Convection
C) Radiation
D) All are same
✅ Answer: C) Radiation
Q58. Why are cooking utensils often made shiny from outside?
A) To absorb heat
B) To reflect radiation and prevent heat loss
C) To look beautiful
D) To reduce weight
✅ Answer: B) To reflect radiation and prevent heat loss
Q59. Why are solar cookers painted black inside?
A) To reflect light
B) To absorb more radiation
C) To look shiny
D) To prevent rusting
✅ Answer: B) To absorb more radiation
Q60. A polished silvered surface is a:
A) Poor absorber, good reflector
B) Good absorber, poor reflector
C) Poor absorber, poor reflector
D) Good absorber, good reflector
✅ Answer: A) Poor absorber, good reflector
Q61. Which type of clothes should we wear in summer?
A) Black
B) Dark-colored
C) Light-colored cotton
D) Heavy woollen
✅ Answer: C) Light-colored cotton
Q62. Why do we feel hot in dark clothes during summer?
A) Dark clothes reflect radiation
B) Dark clothes absorb more radiation
C) Dark clothes emit less heat
D) Dark clothes are heavy
✅ Answer: B) Dark clothes absorb more radiation
Q63. Which statement is true about radiation?
A) Needs medium to travel
B) Travels as waves
C) Only occurs in solids
D) Only occurs in liquids
✅ Answer: B) Travels as waves
Q64. Which of these is a good absorber of heat?
A) Polished metal
B) White cloth
C) Black rough surface
D) Glass sheet
✅ Answer: C) Black rough surface
Q65. Which of these keeps water hot for a long time in a thermos flask?
A) Shiny surface prevents heat loss by radiation
B) Plastic lid
C) Vacuum
D) All of these
✅ Answer: D) All of these
Q66. The primary mode of heat transfer in space is:
A) Conduction
B) Convection
C) Radiation
D) Evaporation
✅ Answer: C) Radiation
Q67. Which surface loses heat fastest by radiation?
A) Black and rough
B) White and shiny
C) Smooth silver
D) Polished aluminium
✅ Answer: A) Black and rough
Q68. Which of these is an example of radiation in daily life?
A) Hand feeling warmth near a fire
B) Spoon getting hot in soup
C) Water boiling in a pot
D) Sea breeze
✅ Answer: A) Hand feeling warmth near a fire
Q69. Radiation heat travels in the form of:
A) Sound waves
B) Light waves
C) Electromagnetic waves
D) Particle motion
✅ Answer: C) Electromagnetic waves
Q70. Why are blankets effective in keeping us warm?
A) They generate heat
B) They absorb heat radiation and trap air
C) They reflect sunlight
D) They are heavy
✅ Answer: B) They absorb heat radiation and trap air
Q71. Radiation can transfer heat through:
A) Solids only
B) Liquids only
C) Vacuum
D) None
✅ Answer: C) Vacuum
Q72. Which of the following materials reflects radiation best?
A) Black paint
B) White cloth
C) Silver polish
D) Dull surface
✅ Answer: C) Silver polish
Q73. Why do desert people prefer white clothes?
A) Absorb more heat
B) Reflect most radiation
C) Look bright
D) Keep cool only at night
✅ Answer: B) Reflect most radiation
Q74. Which phenomenon allows Earth to receive heat from the Sun?
A) Conduction
B) Convection
C) Radiation
D) Insulation
✅ Answer: C) Radiation
Q75. Which of the following is the best absorber of radiant heat?
A) White marble
B) Black board
C) Shiny steel
D) Polished wood
✅ Answer: B) Black board
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