CBSE – 7th Standard Science

Question Bank – Chapter 4 – Heat

CHAPTER 4

HEAT

 

Q1. How do we feel and measure Temperature?

Ans. Some objects are hot some objects are cold around us .A reliable measure of the hotness of an object is its temperature. Temperature is measured by a device called thermometer.

 

Q2. How many types of Thermometer are generally used? 

Ans. The thermometer that measures our body temperature is called a clinical thermometer and another type of thermometer used is the laboratory thermometer. The clinical thermometer has the range 35oC to 42oc and range of a laboratory thermometer is generally from 10°C to 110°C.

 

 

Q 3.  What precaution should be taken while taking reading from a  thermometer?

Ans. A clinical thermometer consists of a long, narrow, uniform glass tube. It has a bulb at one end. This bulb contains mercury. Outside the bulb, a small shining thread of mercury can be seen . Read temperature with a scale on the thermometer.  Thermometer should be washed before and after use, preferably with an antiseptic solution.  Ensure that before use the mercury level is below 35°C. Read the thermometer keeping the level of mercury along the line of sight. Handle the thermometer with care

 

Q.4  What do you understand by the term conductors and non conductors?

Ans. The materials which allow heat to pass through them easily are conductors of heat. For example, aluminum, iron and copper. The materials which do not allow heat to pass through them easily are poor conductors of heat such as plastic and wood.

 

Q5. Explain in which ways heat is transferred from one object to another?

Ans. There are three ways in which heat can flow from one object to another. These are conduction, convection and radiation. In solids, generally, the heat is transferred by conduction. In liquids and gases the heat is transferred by convection.

 

 

Q6.How does heat passes through or transferred solids?

Ans. The heat is, transferred from a hotter object to a colder object from the end nearest to the flame. The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction. In solids, heat is transferred by the process of conduction.

Q7.  What happens in coastal areas when the temperature of water and land varies?

Ans. In the coastal areas land gets heated faster than the water. The air over the land becomes hotter and rises up. The cooler air from the sea rushes in towards the land to take its place. The warm air from the land moves towards the sea to complete the cycle. The air from the sea is called the sea breeze.  At night the water cools down more slowly than the land. So, the cool air from the land moves towards the sea. This is called the land breeze.

 

Q8. Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing?

Ans. Wool is a poor conductor of heat. Moreover, there is air trapped in between the wool fibres. This air prevents the flow of heat from our body to the cold surroundings. So, we feel warm.

 

Q9. Explain the process of Radiation?

Ans. From the sun the heat comes to us by another process known as radiation. The transfer of heat by radiation does not require any medium.

 

Q.10. What do you mean by convection?

Ans. When water is heated, the water near the flame gets hot. Hot water rises up. The cold water from the sides moves down towards the source of heat. This water also gets hot and rises.

 

Q.11. Is it possible to construct buildings that are not affected much by heat and cold outside? Explain

Ans. Yes, it is possible to construct buildings that are not affected much by heat and cold outside. We often use electricity and fuels like coal and wood to keep our houses cool or warm. This can be done by constructing outer walls of buildings so that they have trapped layers of air. One way of doing this is to use hollow bricks, which are available these days

 

Q.12. why it is more comfortable to wear white or light-coloured clothes in the summer

Ans. It is more comfortable to wear white or light-coloured clothes in the summer and dark-coloured clothes in the winter Light-colored clothes reflect most of the heat that falls on them and, therefore, we feel more comfortable wearing them in the summer.

 

 

 

 

 

CBSE 7th Standard Science

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CBSE 7th Standard Science Syllabus and Revision Notes

  • Chapter 1 – Nutrients in plants
  • Chapter 2 – Nutrition in Animals
  • Chapter 3 – Fibre to Fabric
  • Chapter 4 – Heat
  • Chapter 5 – Acids bases and salts
  • Chapter 6 – Physical and Chemical Changes
  • Chapter 7 – Weather, Climate and Adaptations of Animals to Climate
  • Chapter 8 – Winds, Storms and Cyclone
  • Chapter 9 – Soil
  • Chapter 10 – Respiration in Organisms
  • Chapter 11 – Transportation in Animals and Plants
  • Chapter 12 – Reproduction in Plants
  • Chapter 13 – Motion and Time
  • Chapter 14 – Electric Current and its Effects
  • Chapter 15 – Light
  • Chapter 16 – Water: A Precious Resource
  • Chapter 17 – Forests: Our Lifeline
  • Chapter 18 – Waste water Story