NCERT Solutions for Class 7 Science Chapter 4 : Heat

Q:

Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
(a) copper bottom makes the pan more durable
(b) such pans appear colourful
(c) copper is a better conductor of heat than the stainless steel
(d) copper is easier to clean than the stainless steel

A:

Correct option is (c).

Explanation:

Copper is a good conductor of heat, so it allows the heat to distribute evenly throughout the utensil, and heats the stainless steel pans faster.

Q:

A wooden spoon is dipped in a cup of ice cream. Its other end
(a) becomes cold by the process of conduction
(b) becomes cold by the process of convection
(c) becomes cold by the process of radiation
(d) does not become cold

A:

Correct option is (d).

Explanation:

Wood is a bad conductor of heat.

Q:

An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
(a) flow from iron ball to water
(b) not flow from iron ball to water or from water to iron ball
(c) flow from water to iron ball
(d) increase the temperature of both

A:

Correct option is (b).

Explanation:

As both the water and the iron ball have the same temperature, so the heat will not flow from iron ball to water or from water to iron ball.

Q:

One litre of water at 30°C is mixed with one litre of water at 50°C. The temperature of the mixture will be
(a) 80°C
(b) more than 50°C but less than 80°C
(c) 20°C
(d) between 30°C and 50°C

A:

Correct option is (d).

Explanation:

As heat will flow from one litre of water at 50°C to one litre of water at 30°C, so the temperature of the mixture will be between 30°C and 50°C.

Q:

In places of hot climate it is advised that the outer walls of houses be painted white. Explain.

A:

The outer walls are advised to be painted white in hot climate conditions because white colour reflects maximum amount of heat back into the surroundings, that falls on it. Therefore, white coloured walls absorb least amount of heat and keep the house cool.

Q:

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

A:

Wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing because in between the multiple layers of clothing, air is trapped that prevents the loss of heat from the body to the surroundings. Air is a poor conductor of heat and prevents the transfer of heat from one region to the other. This trapped air in between the layers of clothing keeps us warmer than the single thick clothing.

Q:

Match the following:
(i) Land breeze blows during (a) summer
(ii) Sea breeze blows during (b) winter
(iii) Dark coloured clothes are preferred during (c) day
(iv) Light coloured clothes are preferred during (d) night

A:

The correctly matched contents of the two given columns are as follows:

(i) Land breeze blows during

(d) Night

(ii) Sea breeze blows during

(c) Day

(iii) Dark coloured clothes are preferred during

(b) Winter

(iv) Light coloured clothes are preferred during

(a) Summer

Q:

Give two examples each of conductors and insulators of heat.

A:

The examples of conductors of heat are as follows:

  1. Aluminium
  2. Copper

The examples of insulators of heat are as follows:

  1. Wood
  2. Rubber

Q:

Look at Fig. 4.13. Mark where the heat is being transferred by conduction, by convection and by radiation.

A:

Various modes of transfer of the heat in the given diagram can be shown as follows:

Q:

Fill in the blanks :
(a) The hotness of an object is determined by its __________.
(b) Temperature of boiling water cannot be measured by a _____________ thermometer.
(c) Temperature is measured in degree ______________.
(d) No medium is required for transfer of heat by the process of __________.
(e) A cold steel spoon is dipped in a cup of hot milk. Heat is transferred to its other end by the process of ______________.
(f ) Clothes of ______________ colours absorb more heat better than clothes of light colours.

A:

(a) The hotness of an object is determined by its temperature.

(b) Temperature of boiling water cannot be measured by a clinical thermometer.

(c) Temperature is measured in degree Celsius.

(d) No medium is required for transfer of heat by the process of radiation.

(e) A cold steel spoon is dipped in a cup of hot milk. Heat is transferred to its other end by the process of conduction.

(f ) Clothes of dark colours absorb more heat better than clothes of light colours.

Q:

State similarities and differences between the laboratory thermometer and the clinical thermometer.

A:

Similarities between clinical and laboratory thermometers are as follows:

  1. Both of them are used for measuring temperature.
  2. Both of them use mercury as an indicator for rise and fall in temperature.

Differences between clinical and laboratory thermometers are as follows:

  1. Clinical thermometer is used to measure body temperature whereas; laboratory thermometer is used to measure temperature of substances.
  2. The range of clinical thermometer is from 35°C to 42°C while that of laboratory thermometer is from minus 10°C to 110°C.

Benefits of NCERT Solutions

Following are some of the benefits of using NCERT Solutions by Extramarks.

1. The NCERT solutions for class 7 are prepared keeping in mind the necessary rules and format issued by the CBSE board thus providing students much-needed preview of the exam pattern of questions and preview of the exam that they are going to face during the final exams.

2. The students can be sure about the quality of the solutions as they are committed by highly experienced and expert teachers. These teachers have years of experience and they make sure that there is no mistake committed when preparing the solutions.

3. The NCERT 7 solutions are provided for the questions that are most likely to appear in the exam thus improving the efficiency of the students by helping them prepare for the important parts of the syllabus.

Tips & Strategies for Class 7 Exam Preparation

1. Start your revision early so you can revise well and grasp all the difficult concepts.

2. Organize your study time by making a timetable as it will help you manage your time accordingly.

3. Take mock tests and solve sample papers as they will help you learn time management during the exam and make you familiar with the exam pattern.

4. Take regular breaks, look after yourself by sleeping properly and eating well.

5. Know your exam well, explore the mock tests, and practice sample papers as much as you can.

Why Choose Extramarks CBSE Class 7 Study Materials?

1. The solutions have been compiled keeping in mind the purpose of scoring high marks in exams thus they have everything that the students need to prepare for exams.
2. The NCERT solutions for class 7 are designed in a clear and simple language complete with diagrams so that the students understand the subject well.
3. The NCERT 7 solutions are accurate thus improving their reliability.
4. The solutions are designed by expert and experienced teachers that help in removing all doubts out of the solutions and improving the credibility of the answers.

Frequently Asked Questions

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Is class 7 Math NCERT book sufficient for prepare for the exams?

Yes, the NCERT book has been designed keeping in mind the pattern of paper that will be presented in the exam to students. The NCERT book is sufficient to study for the exam as it has everything related to the exam and contains all information out of which the questions will be asked in the exam. But if you want to prepare a little bit extra, we suggest that you go through the NCERT class 7 solutions.

When to refer to NCERT solutions for class 7th?

When you are studying the NCERT book for math and other subjects for your class 7 exams, refer to the NCERT class 7 solutions simultaneously so you can see where you are going wrong and what are you getting right in your exercises’ attempt.

Why are the NCERT solutions important for Class 7th?

The class 7th is very crucial as it is among the major middle school classes during which the child’s base is formed in math and science and even in other subjects like English. Thus, it is students must study smartly in this class and ace their exams while getting all the help they need from the NCERT 7 solutions given by Extramarks.

Can I rely on the NCERT solutions for class 7 Math at Extramarks to perform well in the annual exam?

Yes, absolutely. The NCERT solutions provided by Extramarks for class 7 are eloquent and elaborate at best and are thus useful for students studying for the final exams of class 7. The students will have many questions and doubts regarding the NCERT solutions for class 7 and this is why the solutions have been elaborated well to help students understand the answers to exercises.

Do you provide NCERT solutions for Class 7 Math for free?

Yes, the NCERT solutions for Math and other subjects for class 7 are available for free from Extramarks.

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