Get the simplified Class 7 Science Extra Questions and Class 7th Curiosity Chapter 7 Heat Transfer in Nature Important Extra Question Answer with complete explanation.
Class 7 Science Chapter 7 Heat Transfer in Nature Extra Questions
Class 7 Science Chapter 7 Extra Questions on Heat Transfer in Nature
Heat Transfer in Nature Class 7 Very Short Question Answer
Question 1.
Which of the following materials is a good conductor of heat: a metal spoon, a wooden spoon, a plastic handle, or a rubber tube?
Answer:
The metal spoon is a good conductor of heat because metals allow heat to flow easily through them.
Question 2.
Why do we use metals in cooking pans instead of wood or plastic?
Answer:
Metals are good conductors of heat, allowing heat to transfer quickly to the food. Wood and plastic are bad conductors and would not heat the food efficiently.
Question 3.
What happens to the temperature of water when it is heated using a metal pot compared to a wooden pot?
Answer:
The metal pot heats up the water faster because metal is a good conductor of heat, while a wooden pot would heat up slower because wood is a bad conductor.
Question 4.
How does convection help in transferring heat from the land to the atmosphere?
Answer:
Convection allows the warm air to rise and spread out, cooling down the land and balancing the temperature differences between the land and the sea.
Question 5.
What is the process called when cool air from the sea moves toward the land during the day?
Answer:
This movement of cool air is called a sea breeze.
Question 6.
How does the sea breeze help people near the beach feel cooler during the day?
Answer:
The cooler air from the sea replaces the warm air, lowering the temperature and making it feel cooler near the beach.
Question 7.
Why do land breezes occur at night instead of sea breezes?
Answer:
At night, the land cools down faster than the sea, causing the air above the land to become cooler and denser. The cool air moves from the land to the sea, creating land breeze.
Question 8.
Why do we feel warm when we stand near a fire even though we are not touching it?
Answer:
The heat we feel near the fire is transferred by radiation in the form of infrared waves, which do not require a medium to travel.
Question 9.
How does the heat from the Sun help in the process of evaporation in the water cycle?
Answer:
The Sun’s heat causes water in rivers, lakes, and oceans to change into water vapor, which rises into the atmosphere.
Question 10.
What happens to the water in lakes and rivers when the weather gets hot, and how does this relate to the water cycle?
Answer:
The heat causes water to change into water vapor and rise into the air, which is part of the process of evaporation in the water cycle.
Question 11.
In the water cycle, how does the process of precipitation help maintain water levels in rivers and lakes?
Answer:
Precipitation brings water back to the Earth from the atmosphere in the form of rain, snow, or hail, which replenishes rivers, lakes, and groundwater.
Heat Transfer in Nature Class 7 Short Question Answer
Question 1.
Differentiate between two modes of transfer of heat, i.e. convection and conduction.
| Conduction | Convection |
| The mode of transfer of heat from the hotter part of the material to its colder part or from a hot material to a cold material in contact with it without the movement of material as a whole. This phenomenon is known as conduction. | The mode of transfer of heat from the hotter part of a fluid to its colder parts by the movement of liquid itself. This phenomenon is known as convection. |
| In all the soids, heat is transferred by the process of conduction. | In all the liquids and gases, heat is transferred by the process of convection. |
Question 2.
During the day, land heats up faster than water, causing wind to blow from the sea to the land. Name this phenomenon and explain how it involves convection. Also, explain how the reverse happens at night.
Answer:
This phenomenon is called a sea breeze. During the day, land gets hotter than the sea, so the air above land becomes warm and rises. Cooler air from the sea moves in to take its place, creating wind from sea to land. At night, land cools faster than water. Now the air above the sea is warmer, rises up, and the cooler air from the land moves toward the sea. This is called a land breeze. This is due to convection, where heat is transferred through the movement of air particles.
Question 3.
Explain the reason for the shiny reflectors of room heaters.
Answer:
The shiny surface absorbs very little heat due to which the reflectors reflect all the heat which makes the room heaters more effective. So, due to this reason, room heaters have shiny reflectors.
Question 4.
During a summer science camp, students touched different trays left in the sun. A metal tray was hot, but a wooden tray was not.
(a) Which method of heat transfer caused the tray to become hot?
(b) Why was the metal tray hotter than the wooden one?
(c) How does this help us in designing safe cooking tools?
Answer:
(a) The tray became hot because of radiation.
(b) Metal is a good conductor of heat, while wood is a poor conductor (insulator).
(c) We use metals for fast heating in cooking, and poor conductors (like plastic or wood) for handles to avoid burns.
Question 5.
Observe the given figure, water is being boiled in a pan of wide base.
(i) Which position P or T will feel warmer?
(ii) Fill up the boxes P and T to indicate the mode of flow of heat to the hand.
Answer:
(i) As in the given diagram, position P will feel warmer because apart from radiation, heat is also transferred via convection at this position.
(ii) The flow of heat to P is a convection process and flow of heat to T is radiation.
Question 6.
At a camp site, there are tents of two shades. One made with black fabric and the other with white fabric. Which one will you prefer for resting on a hot summer afternoon? Give reason for your choice. Would you like to prefer the same tent during winter?
Answer:
We will prefer white fabric tent in case of summer because it reflects all the radiations from the sun and keeps us cool inside the tent. But in case of winter, we should not use white fabric tent, we should use black fabric tent as it absorbs all colour of light from the sun and keeps us warm inside.
Question 7.
Ravi wears a black T-shirt in summer and feels hotter than his friend wearing a white shirt. Explain the reason using the process of radiation. Why do dark colored clothes feel warmer in sunlight?
Answer:
This is due to radiation, where heat travels without a medium. Black surfaces absorb more heat radiation from the sun, while white surfaces reflect most of it. Therefore, Ravi’s black T-shirt absorbs more sunlight, making him feel hotter.
Question 8.
What is the significance of the water cycle?
Answer:
Water is required for survival of all living and non living organisms. The water cycle is critical because it ensures that water is available to all living organisms and regulates weather patterns on our planet. Water that falls on land collects in rivers and lakes, soil, and porous rock layers, and much of it flows back into the oceans to evaporate.
Question 9.
After heavy rainfall, water collected on the field slowly disappeared.
(a) Name two natural processes responsible.
(b) Which one helps recharge groundwater?
(c) Why is this important in villages?
Answer:
(a) Evaporation and infdtration.
(b) Infiltration helps recharge groundwater, as water seeps into the soil and fills underground water layers.
(c) Villages use groundwater for drinking and farming, as infiltration keeps wells full.
Question 10.
How are plants responsible for water conservation?
Answer:
The roots of plants and trees hold the soil tightly, slowing the flow of rainwater on land and improving its absorption by the soil. As a result, if we plant more trees, the soil will absorb more rainwater, preserving groundwater.
Heat Transfer in Nature Class 7 Long Question Answer
Question 1.
Last Sunday, Pooja on her week off entered in her kitchen to cook rice for her family in lunch time. The moment she put fry pan on the gas stove and lighted it through the matchstick, all of sudden her 5 years small daughter entered into the kitchen and tends to touch the hot fry pan. At the same time, Pooja saw her and pushed her away from the hot fry pan. In this way, she saved her child.
(i) Explain why are the fry pan provided with the plastic handles?
Answer:
As we know that plastic is a bad conductor of heat which does not allow the heat to pass through itself. So, heat from the fry pan does not flow to the handle due to which we can hold it easily. That’s why, the fry pans are provided with the plastic handles.
(ii) Mention the values represented by Pooja here towards her 5 years small daughter.
Answer:
The value showed by Pooja here is great concern and care towards her 5 years old small daughter.
Question 2.
In the arrangements A and B as shown in figure, pins P and Q are fixed to a metal loop and an iron rod with the help of wax. In which case are both the pins likely to fall at different times? Explain.
Answer:
As in the given figures (a) and (b), in case (a) P and Q gets equal heat, so pin fix at P and Q in case of (a) fall simultaneously.
But in case of (b), the pin at point P falls first, followed by the pin at Q, because point P receives more heat than point Q during the same time.
Question 3.
Explain the water cycle process with a labelled diagram.
Answer:
The water cycle shows the continuous flow of water within the earth and the atmosphere. Water molecules are transferred from the oceans and land surface into the atmosphere by evaporation, dropped on the land as precipitation and moved back to the sea by rivers and groundwater. This endless circulation of water is known as the water cycle.
Question 4.
(i) How can we conserve water?
(ii) What is the role of water in the life of plants and animals?
Answer:
(i) There are several modes for conserving water. Here are some essential water conservation practices
(a) Taking baths in a bucket and avoiding showers.
(b) Ensure water from overhead tanks does not overflow
(c) Turn off the water while brushing our teeth.
(d) Wash fruits and vegetables in a water bowl instead of under running water.
(e) Using the water used to wash vegetables to water garden plants.
(ii) Water is used for various purposes, including agriculture, industry, cooking, cleaning utensils, bathing, washing clothes, and most importandy, drinking.
Water is a valuable resource because our daily activities rely solely on water. Water can be found everywhere but is not always drinkable or usable. Even though the seas are abundant in water, we cannot drink or use it as it is saline. Water aids in the nutrition of animals and plants.
Plants require water to absorb nutrients from the soil and produce food. Plants would die without water, and we would lose greenery. It, in turn, would mean the end of all life on earth because there would be no food, oxygen, or rainfall without plants. Thus, it is valuable.
Heat Transfer in Nature Class 7 Case Based Questions
Question 1.
Reema pours hot water into two types of cups. One cup is made of ceramic and the other is made of paper. She records the temperature of water in the cups after 5 min.
| Temperature of the hot water | Temperature of water in the cup after 5 min | |
| Ceramic cup | 90°C | 75°C |
| Paper cup | 90°C | 60°C |
(i) What is Reema testing?
(a) Is paper a bad conductor of heat?
(b) Does the shape of a cup prevent loss of heat?
(c) Does the colour of a cup prevent loss of heat?
(d) Is paper a better conductor of heat than ceramic?
Answer:
(d) Is paper a better conductor of heat than ceramic?
(ii) Would there be a change in the temperature readings if both the cups were covered with a lid ? Explain.
Answer:
If both the cups were covered with a lid, the readings of temperature would be higher as lids would not allow heat to escape.
Question 2.
A small village named Sundarpur was facing dry weather for weeks. The lake in the village had dried up, and farmers were worried. One day, the sky turned cloudy, and it started raining. Villagers saw water flowing back into the lake and some water going into the ground. Later, they drew water from wells again. Students of Class 7 studied this natural event and linked it with the water cycle.
(i) Which part of the water cycle helped form the clouds seen in Sundarpur? Explain the process.
Answer:
The process is condensation. Water vapour from lakes and rivers rises up and cools in the atmosphere, changing into tiny water droplets that come together to form clouds.
(ii) How did the rainwater help refill both the lake and the village wells? Mention the two different processes involved.
Answer:
Runoff: Rainwater flows over the ground and collects in lakes and rivers.
Infiltration: Some of the rainwater seeps into the soil and becomes groundwater, which fills wells.
(iii) What role did the Sun play before it rained in?
Answer:
The sun provides heat energy that causes evaporation of water from lakes, rivers, and soil, changing it into water vapour and starting the water cycle.
Heat Transfer in Nature Class 7 Skill Based Questions
Question 1.
The question assesses the student’s ability to identify and explain heat transfer process in real life Situations
(i) By what method of heat transfer does heat energy from the sun reach the earth?
(ii) Select the process of heat transfer which causes a breeze (wind) over land and sea.
(a) Conduction
(b) Convection
(c) Radiation
(iii) Explain in terms of heat transfer, why houses at coastal areas often have their windows facing the sea?
(iv) Suggest two domestic insulation techniques that the houses build at coastal areas could have to maintain constant temperatures.
Question 2.
If a person touches a metal chair and a wooden chair that are both in a sunlit room, why will the metal chair feel much hotter to the person?
Answer:
The metal chair feels much hotter because metal is a good conductor of heat, while wood is a poor conductor of heat. Both chairs get heated by the sunlight and become warm. But when we touch, then the metal chair quickly transfers its heat to our hands, so it feels hotter. On the other hand, wood does not transfer heat easily, so it feels less hot. This is why, the metal chair feels much hotter than the wooden chair, even though both are kept in the same sunlight.
Question 3.
Boiling hot water is poured into a glass with thick bottom. What is likely to happen?
Answer:
When boiling hot water is poured into a glass with a thick bottom, the glass may crack or break. This is because the bottom of the glass becomes hot quickly, but the upper part stays cooler. The glass expands unevenly and this can cause it to crack due to sudden change in temperature.
Question 4.
When ice is added to water in a glass, why do we feel cold when we touch the glass?
Answer:
When ice is added to water, the temperature of the glass also becomes low. When we touch the glass, heat flows from our hand to the cold glass. As a result, we lose heat from our hand and we feel cold. This happens because heat always flows from a warmer object to a colder one.
Heat Transfer in Nature Extra Questions for Practice
Question 1.
How do you define heat flow?
Question 2.
Describe in brief about term convection?
Question 3.
Why convection is not possible in solids? Explain
Question 4.
Name the process through which the heat of sun reaches us.
Question 5.
Explain why does a shiny tea pot stay hotter than a dull brown pot?
Question 6.
What is the role of the sun in the water cycle?
Question 7.
Explain how sea breeze occurs using the concept of heat transfer.
Question 8.
Explain conduction, convection, and radiation with suitable examples. Also mention in which states of matter each method generally occurs.
Question 9.
Describe in detail how land breeze and sea breeze take place?