NCERT Class 7 Science MCQ | Chapter 7: Heat Transfer in Nature
1. What is heat?
(A) A form of energy that flows from a hotter object to a colder object
(B) A substance that has no energy
(C) A type of matter
(D) A form of sound
Answer: (A) A form of energy that flows from a hotter object to a colder object
2. In which direction does heat naturally flow?
(A) From a colder object to a hotter object
(B) From a hotter object to a colder object
(C) From a smaller object to a larger object
(D) From a darker object to a lighter object
Answer: (B) From a hotter object to a colder object
3. Which of the following is a method of heat transfer?
(A) Conduction
(B) Reflection
(C) Evaporation only
(D) Respiration
Answer: (A) Conduction
4. What is conduction?
(A) Transfer of heat through a substance without the bulk movement of the substance
(B) Transfer of heat only through empty space
(C) Movement of a substance from one place to another
(D) Transfer of sound through air
Answer: (A) Transfer of heat through a substance without the bulk movement of the substance
5. Which materials are generally good conductors of heat?
(A) Metals
(B) Wood
(C) Plastic
(D) Rubber
Answer: (A) Metals
6. Which of the following is generally a poor conductor of heat?
(A) Copper
(B) Aluminium
(C) Iron
(D) Wood
Answer: (D) Wood
7. Why are the handles of many cooking utensils made of plastic or wood?
(A) These materials are poor conductors of heat
(B) These materials produce heat
(C) These materials are metals
(D) These materials increase the temperature of food
Answer: (A) These materials are poor conductors of heat
8. What is convection?
(A) Transfer of heat by the movement of a fluid
(B) Transfer of heat only through solids
(C) Transfer of heat through empty space only
(D) Transfer of sound through a liquid
Answer: (A) Transfer of heat by the movement of a fluid
9. Which of the following can transfer heat by convection?
(A) Water
(B) Iron rod only
(C) Wooden block only
(D) Glass sheet only
Answer: (A) Water
10. Why does heated water rise upward?
(A) Heated water becomes less dense and tends to rise
(B) Heated water becomes heavier
(C) Heated water loses all its energy
(D) Heated water becomes a solid
Answer: (A) Heated water becomes less dense and tends to rise
11. What happens to cooler water during convection in a container?
(A) It tends to move downward
(B) It always moves upward
(C) It changes directly into ice
(D) It disappears
Answer: (A) It tends to move downward
12. Which method of heat transfer does not require a material medium?
(A) Radiation
(B) Conduction
(C) Convection
(D) All of these require a medium
Answer: (A) Radiation
13. How does heat from the Sun reach the Earth?
(A) Mainly through radiation
(B) Through conduction
(C) Through convection in space
(D) Through contact between the Sun and Earth
Answer: (A) Mainly through radiation
14. Which surface generally absorbs more radiant heat?
(A) A dark, dull surface
(B) A shiny, polished surface
(C) A transparent surface only
(D) A white surface in every case
Answer: (A) A dark, dull surface
15. Which type of surface is generally a good reflector of radiant heat?
(A) Shiny and polished surface
(B) Dark and dull surface
(C) Rough black surface
(D) Charcoal surface
Answer: (A) Shiny and polished surface
16. Why are light-coloured clothes preferred in hot weather?
(A) They reflect more of the Sun’s radiation than dark-coloured clothes
(B) They absorb all the heat
(C) They produce heat
(D) They prevent all forms of heat transfer
Answer: (A) They reflect more of the Sun’s radiation than dark-coloured clothes
17. Why are dark-coloured clothes generally warmer in sunlight?
(A) They absorb more radiant heat
(B) They reflect all radiant heat
(C) They do not interact with sunlight
(D) They produce cold air
Answer: (A) They absorb more radiant heat
18. Which of the following is an example of conduction?
(A) A metal spoon becoming hot when placed in hot tea
(B) Warm air rising
(C) Heat from the Sun reaching Earth
(D) Sea breeze forming
Answer: (A) A metal spoon becoming hot when placed in hot tea
19. Which of the following is an example of convection?
(A) Water circulating while being heated
(B) A metal rod becoming hot from one end
(C) Heat reaching Earth from the Sun
(D) A shiny surface reflecting sunlight
Answer: (A) Water circulating while being heated
20. Which of the following is an example of radiation?
(A) Feeling the warmth of sunlight
(B) Heating one end of an iron rod
(C) Water circulating in a pan
(D) Warm air rising from a heater
Answer: (A) Feeling the warmth of sunlight
21. What causes sea breeze during the daytime?
(A) Land heats faster than water, causing air movement
(B) Water always becomes hotter than land during the day
(C) There is no temperature difference between land and water
(D) The Moon heats the land
Answer: (A) Land heats faster than water, causing air movement
22. During the daytime, air above the land becomes warm and:
(A) Rises upward
(B) Sinks downward
(C) Becomes solid
(D) Stops moving completely
Answer: (A) Rises upward
23. What is a land breeze?
(A) A breeze that generally blows from land towards the sea at night
(B) A breeze that always blows from sea to land during the day
(C) A wind that occurs only in mountains
(D) A wind caused by rainfall only
Answer: (A) A breeze that generally blows from land towards the sea at night
24. Why does air movement occur due to convection?
(A) Heating causes differences in temperature and density in the fluid
(B) Heating always makes all parts of a fluid equally dense
(C) Fluids cannot move when heated
(D) Convection occurs only in solids
Answer: (A) Heating causes differences in temperature and density in the fluid
25. Which statement correctly describes the three main methods of heat transfer?
(A) Conduction mainly occurs through direct contact, convection involves movement of fluids, and radiation can transfer heat without a material medium
(B) Conduction occurs only in gases, convection occurs only in solids, and radiation requires direct contact
(C) All three methods require direct contact between objects
(D) Radiation occurs only in liquids
Answer: (A) Conduction mainly occurs through direct contact, convection involves movement of fluids, and radiation can transfer heat without a material medium
