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Class 7 Science: Heat Transfer in Nature, 8 practice questions with answers

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These are 8 practice questions on Class 7 Science Chapter 7, Heat Transfer in Nature, of the new NCERT textbook, Curiosity. Each has a worked answer and the textbook page it comes from. They cover conduction in a spoon, where to put an air conditioner and a heater, how ice cools a glass of water, telling sea breeze from land breeze, how the Sun's heat reaches us, the colour of a water tank, what the water cycle does and does not do, and why concrete ground lets less rain soak in. Try each one before you open the answer.

These questions are our own, drafted with AI help, and every answer was checked against the textbook page it cites, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity: Textbook of Science for Grade 7, Chapter 7, printed pages 89 to 104):

7.1 Conduction of heat

Question 1. A steel spoon is left standing in a bowl of hot dal, and soon its handle feels hot. Riya says, "Hot particles of dal climbed up the spoon to the handle." Find her mistake. How did the heat reach the handle?

Answer: by conduction, and no particles travelled up the spoon. Steel is a metal and a good conductor of heat. The particles of the spoon in the hot dal get heated and pass the heat to their neighbours, which pass it on, up to the handle. In conduction, the particles themselves stay where they are; only the heat moves along the spoon. (Conduction and good conductors, page 91.)

7.2 Convection, and land and sea breeze

Question 2. In a room, an air conditioner is usually fitted high up on the wall, while a room heater works best when it stands near the floor. Explain both choices using convection.

Answer: cool air sinks and warm air rises, so each device sets up a current through the whole room. Air cooled by the air conditioner becomes heavier and comes down, and warmer air rises to take its place and gets cooled in turn. Air warmed by a heater near the floor expands, becomes lighter and rises, and cooler air comes down towards the heater to be warmed. In both cases the air of the room is heated or cooled by the actual movement of air: convection. (Warm air rises, page 93; convection, page 94.)

Question 3. An ice cube floats at the top of a glass of water. Does the water near the bottom of the glass also get cold, even though the ice never goes there? Explain.

Answer: yes, by convection. The water touching the ice cools, becomes heavier and moves down. Warmer water from below rises to take its place, is cooled by the ice and sinks in turn. This movement of water carries the cooling through the whole glass. It is the same process the book shows for heated water, working the other way round: there the warm water rises, here the cold water sinks. (Convection in water, page 94.)

Question 4. On a beach, the flags on a lifeguard tower point towards the land in the afternoon and towards the sea late at night. Which breeze is blowing at each time, and why does the direction change?

Answer: a sea breeze in the afternoon and a land breeze at night. A flag streams in the direction the wind is blowing. In the afternoon the wind blows from the sea to the land: by day the land heats up faster than the sea, warm air over the land rises, and cooler air moves in from the sea, which is a sea breeze. At night the land cools faster than the sea, warm air over the sea rises, and cooler air moves from the land to the sea, which is a land breeze. (Sea breeze, page 95; land breeze, page 96.)

7.3 Radiation

Question 5. Kavi says, "The Sun's heat reaches the Earth by convection, carried along by moving air." Find his mistake.

Answer: the Sun's heat reaches us by radiation, which needs no medium. Convection needs a liquid or a gas whose particles move and carry the heat, and conduction also needs a medium. Radiation is the only one of the three processes that needs no medium, and the book says the heat of the Sun reaches us through radiation. (Radiation, page 96; conduction and convection need a medium, page 97.)

Question 6. Ravi wants the water in his family's roof-top tank to stay as cool as possible in summer, so he paints the tank black. Is that a good choice? What colour would be better, and why?

Answer: no; a white or light-coloured tank would stay cooler. The tank is heated by radiation from the Sun. Dark surfaces absorb more of the heat that falls on them, so a black tank would heat the water more. Light-coloured surfaces reflect most of the heat, so a white tank keeps the water cooler. This is the same reason light-coloured clothes are more comfortable in summer. (Light and dark surfaces, page 96.)

7.4 Water cycle, and seepage of water

Question 7. Meera says, "The water cycle makes new water every year, so we can never run out of water." Find her mistake.

Answer: the water cycle does not make new water; it moves the same water around. In the water cycle, water evaporates, condenses into clouds, falls as rain, snow or hail, and flows back to the water bodies. This redistributes and replenishes water in rivers, lakes and oceans, and it conserves the total amount of water on the Earth, but it does not add to it. Water can still run short in a place, for example when groundwater is used up faster than rain refills it. (Water cycle, page 98; groundwater getting depleted, page 100.)

Question 8. A school covers its muddy playground with concrete. Arjun says, "The same rain falls on it as before, so the ground below will get just as much water as before." Find his mistake.

Answer: concrete blocks infiltration, so much less rainwater seeps into the ground. Rainwater reaches the groundwater by seeping through the spaces between soil and rock particles. This is infiltration, and it needs spaces that are wide, open and connected. Concrete covers the soil and leaves no open spaces for the water to enter, so most of the rain runs off instead of soaking in. The book names more concrete surfaces in towns and cities as one reason why less water infiltrates and groundwater is getting depleted. (Infiltration and concrete surfaces, page 100.)

Questions students ask

What are conduction, convection and radiation? The three ways heat moves. In conduction, heat passes from particle to particle while the particles stay in place, as in a metal spoon. In convection, the particles of a liquid or gas move and carry the heat, as in boiling water. In radiation, heat travels without any medium, as from the Sun or a fire. (Pages 91 to 97 and 101 to 102.)

What are good and bad conductors of heat? Materials that let heat pass through easily, such as metals, are good conductors. Materials that do not, such as wood, glass, clay, porcelain and air, are poor conductors, also called insulators. (Pages 91 and 92.)

What are land breeze and sea breeze? By day the land heats faster than the sea, so cooler air moves from the sea to the land: a sea breeze. At night the land cools faster, so cooler air moves from the land to the sea: a land breeze. (Pages 95 and 96.)

What is the water cycle? The continuous movement of water, up as water vapour and down as rain, snow or hail, through soil, rocks and plants and back to water bodies. This is the water cycle in the Class 7 Science chapter. (Page 98.)

Why are hollow bricks used in hot regions? The air trapped in hollow bricks is a poor conductor of heat, so the walls let less heat through, keeping the house cool in summer and warm in winter. (Page 92.)

Where are the extra questions and MCQs? The 8 questions above are extra practice with worked answers and pages, and the free practice set below marks multiple-choice questions instantly.

Where are the notes? The chapter's own summary, "In a Nutshell", is on pages 101 and 102; the facts list at the top of this page follows it.

Practise more, and check your marks

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Sources

All opened and read on 22 October 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 88.

The facts are from the textbook pages above. The questions and worked answers are our own. This guide is general information; follow your teacher and the textbook.