CBSE Class 7 Science Chapter 7: Heat Transfer in Nature — Assertion & Reason
CBSE Class 7 Science Assertion & Reason
Expert crafted · Instant PDF download · 2026-27
The following Assertion and Reason questions are based on Chapter 7: Heat Transfer in Nature from the NCERT Class 7 Science textbook Curiosity. Each question has four options — read both the Assertion (A) and Reason (R) carefully before selecting your answer.
How to attempt Assertion & Reason questions:
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is NOT the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion & Reason Questions
1
Assertion (A): Cooking utensils are generally made of metals like copper or aluminium.
Reason (R): Metals are good conductors of heat and allow heat to pass through them quickly.
Reason (R): Metals are good conductors of heat and allow heat to pass through them quickly.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Metals efficiently transfer heat from the stove to the food, which is why they are the primary materials used for cooking vessels.
2
Assertion (A): The handles of cooking utensils are typically made of plastic or wood.
Reason (R): Plastic and wood are poor conductors (insulators) of heat, preventing our hands from getting burnt.
Reason (R): Plastic and wood are poor conductors (insulators) of heat, preventing our hands from getting burnt.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Since insulators do not transfer heat easily, they keep the handles cool enough to be held safely while the metal pan is hot.
3
Assertion (A): Heat always flows naturally from an object at a lower temperature to an object at a higher temperature.
Reason (R): Heat transfer between two objects in contact continues until both objects reach the exact same temperature.
Reason (R): Heat transfer between two objects in contact continues until both objects reach the exact same temperature.
Answer: (d)
A is false, but R is true. Heat always flows naturally from a hotter object (higher temperature) to a colder object (lower temperature), never the reverse.
4
Assertion (A): Conduction is the primary mode of heat transfer in solid objects.
Reason (R): In conduction, heat is transferred through the actual physical movement of particles from one end of the object to the other.
Reason (R): In conduction, heat is transferred through the actual physical movement of particles from one end of the object to the other.
Answer: (c)
A is true, but R is false. In conduction, heat is transferred by particles vibrating and passing energy to their neighbours without actually leaving their positions. The actual physical movement of particles happens in convection.
5
Assertion (A): Water and air are poor conductors of heat.
Reason (R): Heat transfer in liquids and gases mainly takes place by the process of convection.
Reason (R): Heat transfer in liquids and gases mainly takes place by the process of convection.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. While both statements are true, the fact that convection occurs in fluids is not the reason they are poor conductors; they are poor conductors because their particles are farther apart.
6
Assertion (A): During the day in coastal areas, cooler air flows from the sea towards the land.
Reason (R): This flow of cooler air from the sea to the land is called the sea breeze.
Reason (R): This flow of cooler air from the sea to the land is called the sea breeze.
Answer: (b)
Both A and R are true, but R is NOT the correct explanation of A. The reason cooler air flows towards land is that land heats up faster than water during the day, causing the hot air above it to rise and creating a low-pressure area that pulls in the sea air.
7
Assertion (A): The outer walls of houses in hot regions are often constructed using hollow bricks.
Reason (R): The trapped air inside the hollow bricks acts as an insulator and keeps the house cool by preventing heat transfer.
Reason (R): The trapped air inside the hollow bricks acts as an insulator and keeps the house cool by preventing heat transfer.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Air is a poor conductor of heat. The hollow spaces trap air, blocking the intense outside heat from conducting through the walls into the living space.
8
Assertion (A): Coastal areas experience a moderate climate without extreme temperature variations.
Reason (R): Large water bodies heat up and cool down much slower than land, regulating the surrounding temperature.
Reason (R): Large water bodies heat up and cool down much slower than land, regulating the surrounding temperature.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The high heat capacity of water means it acts as a thermal buffer, preventing the nearby land from getting too hot in the summer or too cold in the winter.
9
Assertion (A): We feel warm when we stand outdoors in the sunlight.
Reason (R): The heat from the Sun reaches the Earth primarily through the process of radiation.
Reason (R): The heat from the Sun reaches the Earth primarily through the process of radiation.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Since there is a vast vacuum between the Sun and the Earth, conduction and convection cannot occur; radiation is the only way solar heat reaches us.
10
Assertion (A): Radiation requires a solid or liquid medium to transfer heat energy.
Reason (R): Heat from the Sun reaches the Earth by travelling through the vacuum of space.
Reason (R): Heat from the Sun reaches the Earth by travelling through the vacuum of space.
Answer: (d)
A is false, but R is true. Radiation is unique because it does not require any material medium to transfer heat; it can travel perfectly well through a vacuum.
11
Assertion (A): Dark-coloured clothes are preferred during the cold winter season.
Reason (R): Dark surfaces are better absorbers of heat radiation than light-coloured surfaces.
Reason (R): Dark surfaces are better absorbers of heat radiation than light-coloured surfaces.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Wearing dark clothes in winter helps us stay warm because the dark fabric absorbs more radiant heat from the Sun.
12
Assertion (A): Light-coloured clothes keep us comfortable during hot summer days.
Reason (R): Light colours reflect most of the heat radiation that falls on them.
Reason (R): Light colours reflect most of the heat radiation that falls on them.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. By reflecting the Sun's radiant heat rather than absorbing it, light-coloured clothes prevent our bodies from overheating.
13
Assertion (A): Woollen clothes keep us exceptionally warm during cold winter days.
Reason (R): Wool is a poor conductor of heat and the air trapped between its fibres prevents body heat from escaping to the cold surroundings.
Reason (R): Wool is a poor conductor of heat and the air trapped between its fibres prevents body heat from escaping to the cold surroundings.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The insulating property of both the wool material itself and the dead air spaces trapped within it effectively locks in our natural body heat.
14
Assertion (A): Two thin blankets joined together provide more warmth than a single thick blanket of the same total thickness.
Reason (R): The layer of air trapped between the two thin blankets acts as an insulator and prevents heat loss.
Reason (R): The layer of air trapped between the two thin blankets acts as an insulator and prevents heat loss.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Since air is a very poor conductor of heat, the extra layer of trapped air adds a significant amount of thermal insulation.
15
Assertion (A): A metal spoon left in a hot cup of tea becomes hot after some time.
Reason (R): Heat is transferred from the hot tea to the metal spoon by the process of convection.
Reason (R): Heat is transferred from the hot tea to the metal spoon by the process of convection.
Answer: (c)
A is true, but R is false. The metal spoon becomes hot due to conduction (heat traveling through the solid metal), not convection.
16
Assertion (A): Smoke and hot air always rise upwards in the atmosphere.
Reason (R): When air is heated, it expands and becomes lighter (less dense) than the surrounding cold air.
Reason (R): When air is heated, it expands and becomes lighter (less dense) than the surrounding cold air.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. The physical expansion of hot air lowers its density, causing it to float upward above the heavier, cooler air.
17
Assertion (A): Sea breeze blows continuously throughout the night in coastal regions.
Reason (R): At night, the land cools down faster than the sea, causing cooler air to flow from the land to the sea.
Reason (R): At night, the land cools down faster than the sea, causing cooler air to flow from the land to the sea.
Answer: (d)
A is false, but R is true. The sea breeze blows during the day. The phenomenon described in the reason—air flowing from the cooler land to the warmer sea at night—is called a land breeze.
18
Assertion (A): Ventilators or exhaust fans in rooms are usually placed near the ceiling.
Reason (R): Warm air, being lighter, rises up and easily escapes through the ventilators located higher up.
Reason (R): Warm air, being lighter, rises up and easily escapes through the ventilators located higher up.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Convection causes hot, stale air to rise to the top of the room, making the ceiling the most effective place to vent it outside.
19
Assertion (A): Room heaters are most effective when they are placed near the floor.
Reason (R): The heated air rises from the floor and sets up convection currents that evenly warm the entire room.
Reason (R): The heated air rises from the floor and sets up convection currents that evenly warm the entire room.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Placing the heater low allows the warm air to naturally rise, circulating heat throughout the living space via convection.
20
Assertion (A): The bottom outer surface of many cooking pans is often painted black.
Reason (R): Black surfaces absorb heat more efficiently, allowing the food inside to cook faster and save fuel.
Reason (R): Black surfaces absorb heat more efficiently, allowing the food inside to cook faster and save fuel.
Answer: (a)
Both A and R are true, and R is the correct explanation of A. Darker surfaces are excellent absorbers of thermal radiation, helping the pan capture the maximum amount of heat from the flame.
❓ Frequently Asked Questions
What is covered in CBSE Class 7 Science Chapter 7 Heat Transfer in Nature?
This chapter covers all key topics from Heat Transfer in Nature as per CBSE 2026-27 syllabus.
Is this Assertion & Reason useful for CBSE board exams?
Yes, designed for CBSE Class 7 board exam preparation covering the complete syllabus.
Are these CBSE Class 7 Science Assertion & Reason updated for 2026-27?
Yes, all content at eBookPublisher is updated as per the latest 2026-27 CBSE syllabus.
How many chapters are in CBSE Class 7 Science?
All chapters of CBSE Class 7 Science are covered at eBookPublisher with free Assertion & Reason for each chapter.
Can I study Heat Transfer in Nature online for free?
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