Class 7 Science · Original EZT practice
Heat Transfer in Nature (Class 7 Chapter 7): summary and practice
Three ways heat travels, and one giant cycle it drives. Chapter 7 starts with pins dropping off a hot metal strip and ends with the water cycle that fills our rivers: conduction through solids, convection in liquids and gases (including the sea breeze that cools the beach), and radiation that needs no medium at all - which is how the Sun warms us across empty space. All questions are original EZT tutor practice following the chapter's own section order.
8 original worked examples, 8 fresh self-check questions and 4 mixed questions, with explained answers. These are not copied textbook exercises, an official chapter index or a full answer key. No affiliation with NCERT is claimed.
Official sources for topic and edition context, checked 18 October 2026:
1. Conduction: heat through solids
In the chapter's activity, pins are fixed along a metal strip and one end is heated (with adult supervision): the pins drop one by one, starting nearest the flame. Heat passes from particle to particle along the solid - this is conduction. Materials that pass heat well (metals) are good conductors; those that do not (wood, plastic) are poor conductors (insulators). That is why cooking pots are metal but their handles are plastic or wood.
2. Convection: heat carried by moving fluids
Liquids and gases carry heat by actually moving: the warm part rises, the cooler part sinks to take its place, and the loop keeps turning - this is convection. The beach shows it on a grand scale: by day, land heats faster than the sea; warm air rises over the land and cooler air flows in from the sea - the sea breeze. At night the land cools faster, the flow reverses - the land breeze.
3. Radiation: heat without a medium
Sit near a fire and you feel warm without touching it - heat reached you by radiation. The Sun's heat crosses the near-empty space to Earth the same way. Heat transfer by radiation does not require any medium. All objects radiate heat: a hot utensil kept away from the flame cools down as it radiates.
4. The water cycle: heat at work
The same heat moves the planet's water: the Sun's radiation evaporates water from oceans, rivers and lakes; the vapour rises, cools and condenses into clouds; water returns as rain or snow; some flows back as rivers, some seeps beneath the ground (groundwater). Snow and glaciers melt in summer to feed rivers, and fresh snow replenishes them in winter.
Choose, solve, check, then try a fresh question.
Before calculating, read the method prompt and name the condition that makes it useful. Write your own attempt. Open the steps only when you need them, and use the check to catch a wrong sign, unit or interpretation. Finish with the fresh question before reading its answer.
Explain the falling order of the pins
Choose the method: Track the heat's path along the strip, not just the final result.
EZT practice question
In the pin-and-strip experiment, why does the pin nearest the flame fall first?
Show the worked solution
- Heat travels along the strip by conduction, from the hot end outward.
- It reaches the nearest pin first.
- The wax holding that pin melts first, so it drops first.
Answer: Heat travels along the strip by conduction, reaching the nearest pin first; its wax melts first, so it drops first. The falling order maps the path of the heat.
Check: The answer links the falling order to the direction the heat moves.
Watch for this: Do not say the nearest pin is simply 'closest to the fire'; the point is that conduction carries the heat along the solid in order.
Now try it yourself
Why do metal pots have plastic or wooden handles?
Check your answer
So the handles stay cool - wood and plastic are poor conductors.
Poor conductors (insulators) do not pass the pot's heat to your hand.
Compare a steel ladle and a wooden spoon in hot soup
Choose the method: Apply the good-conductor vs poor-conductor test to each handle.
EZT practice question
A steel ladle and a wooden spoon rest in the same pot of hot soup. Which handle gets hot, and why does the other stay cool?
Show the worked solution
- The steel handle warms - metal is a good conductor and carries heat up from the soup.
- The wooden handle stays cool - wood is a poor conductor (an insulator).
Answer: The steel handle gets hot because metal conducts heat up from the soup; the wooden handle stays cool because wood is a poor conductor.
Check: Both halves of the answer use the same property - conductivity - in opposite directions.
Watch for this: Do not say the wooden spoon 'blocks' heat; it simply conducts it very poorly.
Now try it yourself
Name two good conductors and two poor conductors of heat.
Check your answer
Good: metals like aluminium and iron. Poor: wood and plastic.
Metals pass heat well; wood and plastic are insulators.
Explain the sea breeze from sand and water temperatures
Choose the method: Ask which surface heats faster, then follow the rising air.
EZT practice question
Palden notices that by day the beach sand is hotter than the sea water, but at night the sand is cooler than the water. Use this to explain the sea breeze.
Show the worked solution
- By day, land heats faster than water, so air above the land warms and rises.
- Cooler air from over the sea moves in to replace it - wind blowing from sea to land.
- At night the land cools faster and the flow reverses (the land breeze).
Answer: By day the land heats faster, warm air rises over it, and cooler air flows in from the sea - that incoming wind is the sea breeze; at night the flow reverses.
Check: The explanation starts from the temperature difference and ends with the wind's direction.
Watch for this: Do not reverse the day-time direction; the breeze blows FROM the sea TO the land.
Now try it yourself
During the day at the beach, which way does the breeze blow?
Check your answer
From the sea towards the land.
Warm air rises over the faster-heating land and cooler sea air moves in.
Explain why smoke and hot air rise above a candle
Choose the method: Follow what heating does to the air's weight and movement.
EZT practice question
Why does the smoke and hot air above a candle rise?
Show the worked solution
- The air near the flame heats up and becomes lighter.
- It rises by convection.
- Cooler air flows in from the sides to replace it, feeding the flame.
Answer: Air near the flame heats up, becomes lighter and rises by convection; cooler air flows in from the sides to replace it.
Check: The rising air and the incoming cooler air are two halves of one convection loop.
Watch for this: Do not say 'heat rises' as if heat itself floats; it is the warmed air that rises.
Now try it yourself
Why does a room cool faster with the window open at the top?
Check your answer
Warm air rises and escapes through the top opening by convection.
Convection carries the warmest air upward, where it can leave the room.
Explain how the Sun heats the Earth
Choose the method: Eliminate the two processes that need a medium, then name the third.
EZT practice question
Conduction needs a solid, convection needs a fluid - how then does the Sun heat the Earth?
Show the worked solution
- Space between the Sun and Earth is nearly empty - no solid, no fluid.
- Conduction and convection therefore cannot carry the Sun's heat.
- Radiation needs no medium at all, so the heat crosses the vacuum of space.
Answer: By radiation, which needs no medium at all; the Sun's heat crosses the near-empty space to reach Earth.
Check: The answer names radiation and the reason the other two fail.
Watch for this: Do not say convection currents in space; there is no fluid medium out there.
Now try it yourself
Which of the three - conduction, convection, radiation - can happen in empty space?
Check your answer
Radiation.
It is the only one of the three that needs no medium.
Name the process that cools a hot utensil
Choose the method: Remember that every object radiates; compare what it loses and gains.
EZT practice question
A hot utensil is removed from the stove and left on the counter. Name the process by which it loses heat to the room even without touching anything.
Show the worked solution
- All objects radiate heat.
- A hot object radiates faster than it receives radiation from the cooler room.
- So it cools down even without contact.
Answer: Radiation - all objects radiate heat, and the hot utensil radiates faster than it receives.
Check: The utensil loses heat without touching anything, which rules out conduction.
Watch for this: Do not reserve radiation only for glowing objects; the chapter says all objects radiate.
Now try it yourself
You feel warm standing near (not above, not touching) a room heater. Which process?
Check your answer
Radiation.
The heat reaches you directly without contact and without rising air carrying it.
Order the water cycle's stages
Choose the method: Start from the Sun's radiation and follow one drop of water.
EZT practice question
Put in order: condensation, evaporation, precipitation.
Show the worked solution
- Evaporation - the Sun's heat turns surface water to vapour.
- Condensation - the vapour rises, cools and forms clouds.
- Precipitation - water falls back as rain or snow.
Answer: Evaporation -> condensation -> precipitation.
Check: Each stage's cause (heat, cooling, falling) matches its position in the order.
Watch for this: Do not put condensation first; vapour must exist before it can condense.
Now try it yourself
Which form of heat transfer drives evaporation in the water cycle?
Check your answer
Radiation from the Sun.
The Sun's radiation evaporates water from oceans, rivers and lakes.
Explain where a summer mountain river's water comes from
Choose the method: Connect the Sun's radiation to melting snow, then to the river.
EZT practice question
Where does the water in a mountain river in summer mostly come from, per the chapter?
Show the worked solution
- The Sun's radiation melts snow and ice in the mountains.
- The meltwater flows down and feeds the rivers.
- Fresh winter snow later replenishes the snow and glaciers.
Answer: Mostly from melting snow and ice in the mountains (converted by the Sun's radiation), later replenished by fresh winter snow.
Check: The answer names both the summer source and the winter replenishment.
Watch for this: Do not credit rainfall as the main summer source in the chapter's account; melting snow is.
Now try it yourself
What is the seeped-underground part of the water cycle called?
Check your answer
Groundwater (water that seeps beneath the ground).
Some of the returning water seeps below the surface instead of flowing back as rivers.
Try a mixed set
Choose a method or explanation before opening each answer.
1. Which process moves heat through a solid metal strip?
Show answer and reason
Conduction.
Heat passes from particle to particle along the solid.
2. What drives the sea breeze?
Show answer and reason
Land heating faster than the sea by day.
Warm air rises over the land and cooler air flows in from the sea.
3. Which process of heat transfer needs no medium?
Show answer and reason
Radiation.
The Sun's heat crosses near-empty space to Earth by radiation.
4. In what order do the water cycle's stages occur?
Show answer and reason
Evaporation, condensation, precipitation.
The Sun's radiation evaporates water, vapour cools into clouds, and water returns as rain or snow.
Try it yourself
Work these on paper before checking any notes. Answers are deliberately not shown here.
- Why does the pin farthest from the flame fall last in the strip experiment?
- Explain the land breeze using what happens to land and sea at night.
- Why do we feel the Sun's warmth even though space is nearly empty?
Know the rule but lose track of the steps?
Bring your book edition, your school topic list and a question you attempted. Ask a tutor to explain the choice of method and test it with a different problem. Agree the lesson topics, schedule and fee before starting.
For cost context, see home tuition fees in Delhi NCR. Agree the topics, schedule and fee with your chosen tutor.
Questions about this practice page
- What is the one-line difference between conduction, convection and radiation?
- Conduction passes heat particle-to-particle through a solid; convection carries it by the bulk movement of a liquid or gas; radiation sends it without any medium.
- Why is the sea breeze cool during the day?
- Land heats faster than water; rising warm air over land pulls in cooler air from over the sea.
- Do all objects radiate heat?
- Yes - hot ones lose heat faster than they gain, which is why a utensil cools off the flame.
- What are poor conductors also called, and give two examples?
- Insulators - wood and plastic (hence pot handles).
- Are these the NCERT exercise questions for Heat Transfer in Nature?
- No. EZT pages are original practice written by our tutors, aligned to the chapter's syllabus - use them to prepare for the textbook exercises, not as a substitute for your book.