CBSE Class 5 EVS Chapter 15 Blow Hot, Blow Cold NCERT Solutions

Reviewed by NCERT Help Editorial Team · Updated on 29 Jul 2026

NCERT Solutions PDF Class 5 PDF

This chapter, 'Blow Hot, Blow Cold,' for CBSE Class 5 Environmental Studies, explores the fascinating concept of using the warmth of our breath. Students will learn how blowing on their hands can either warm them up when cold or cool them down when hot. The solutions cover practical examples like cooling hot food, warming cold hands, and even making sounds by blowing. Through interactive questions and explanations, this chapter helps young learners understand the basic principles of heat transfer and air temperature in everyday situations. These NCERT Solutions provide clear, step-by-step answers to textbook questions, aiding students in grasping the scientific concepts and preparing effectively for their exams.

Home

Quick info

Board	CBSE
Class	Class 5
Subject	Environmental Studies
Session	2026
Language	English
Type	NCERT Solutions
Chapter	15 Blow Hot, Blow Cold

Chapter summary

Chapter 15, 'Blow Hot, Blow Cold,' for Class 5 EVS focuses on the dual nature of breath: its ability to provide warmth and coolness. The NCERT Solutions address how students use their breath to warm cold hands, cool hot food like potatoes or tea, and other everyday applications. It also touches upon making sounds by blowing air through different objects, encouraging observation and experimentation.

Learning outcomes

Understand how blowing air can be used for both warming and cooling.
Identify everyday situations where breath warmth is utilized.
Explain the difference in feeling when blowing hot or cool air.
Experiment with making sounds by blowing through various objects.
Relate personal experiences to scientific concepts of temperature.

Topics covered

Paper topics

Using breath for warming hands
Using breath for cooling hot food
Temperature difference of blown air
Effect of distance on blown air temperature
Cooling methods for food
Making sounds by blowing
Everyday applications of breath temperature

Important topics

Dual use of breath (warming/cooling)
Cooling hot food safely
Observing temperature changes
Practical applications in daily life

PDF preview

Read page by page below. PDF is streamed from the official NCERT website — no download button on this page.

Loading document …

Page of

Loading page …

Questions and Solutions

Do This - Question 1

Have you warmed your hands in winter by blowing on them when they are cold? How does it feel?

Solution: Yes, I have experienced warming my hands by blowing on them in winter when they felt cold. It feels quite comfortable and soothing as the warmth from my breath helps to raise the temperature of my hands.

Do This - Question 2

Blow hard from your mouth onto your hands. How did you find the air from your mouth as compared to the air around? Was it hotter or cooler?

Solution: When I blow hard from my mouth onto my hands, the air feels noticeably warmer compared to the surrounding air. This is because the air coming from my mouth is at body temperature, which is higher than the ambient temperature.

Do This - Question 3

Now put your hands at some distance from your mouth and blow again. Does the air from your mouth feel warm? Why?

Solution: When my hands are held at some distance from my mouth, the air blown from my mouth does not feel as warm. This is because as the air travels through the space between my mouth and my hands, it mixes with the cooler surrounding air, losing some of its initial warmth.

Think and Tell - Question 1

Can you think of any other way in which you use the warmth from your breath?

Solution: Yes, another way the warmth from our breath can be used is for temporary relief from eye irritation or minor discomfort. Sometimes, a part of a handkerchief is warmed by blowing on it, and then this warm cloth is gently placed over the eyes or an injured area to provide comfort.

Think and Tell - Question 2

Fold a piece of cloth 3-4 times. Now bring it close to your mouth and blow hard on it. Did the cloth become warm?

Solution: Yes, when I fold a piece of cloth several times and blow hard on it, the cloth does become warm. The concentrated warm air from my breath transfers heat to the fabric.

Think and Tell - Question 3

Balishtiye saw that the woodcutter was trying to cool the hot potatoes by blowing on them. What would have happened if he had eaten the potatoes without cooling them?

Solution: If the woodcutter had eaten the potatoes without cooling them, he would have likely burnt his mouth and tongue. Eating food that is too hot can cause injury to the sensitive tissues inside the mouth.

Think and Tell - Question 4

Have you ever burnt your tongue when you ate or drank something that was too hot? How do you cool some food when it is too hot?

Solution: Yes, I have sometimes burnt my tongue when eating very hot food, like pakodis, or sipping hot tea. To cool down hot food, I usually blow gently over its surface. Sometimes, using a small fan or simply waiting for it to cool naturally are also effective methods.

Think and Tell - Question 5

If you were to cool these three hot things—dal, roti, rice—in which ways would you do so?

Solution: To cool hot dal, roti, or rice, I would use a combination of methods. Blowing gently over the surface of the food helps to dissipate heat. Spreading the food out in a broader, flatter container also increases the surface area exposed to the air, speeding up the cooling process. Using a fan can also be effective.

Think and Tell - Question 6

For what other things do you blow air from your mouth?

Solution: Besides cooling or warming, I blow air from my mouth for several other activities, such as:

Making a whistling sound.
Playing certain musical instruments like a flute or harmonica.
Removing dust or small particles from objects like spectacles or electronic devices.
Inflating balloons.
Making sounds with things like a toffee wrapper or a leaf.

Picture 1 - Question 7

Mini tried to cool her tea by blowing on it. Which do you think will be hotter—Mini's tea or the air she blew from her mouth?

Solution: Mini's tea would be hotter than the air she blew from her mouth. The air she exhales is at her body temperature, which is much lower than the temperature of freshly made hot tea.

Picture 2 - Question 8

Sonu was feeling very cold. He kept blowing on to his hands. Now think and write, which will be cooler-Sonu's hands or his breath?

Solution: Sonu's hands will be cooler than his breath. Since Sonu is feeling cold, his body temperature might be lower, but his breath is still warmer than his cold hands. By blowing on his hands, he is transferring warmth from his breath to his hands.

Blow in Different Ways - Question 1

Make whistles of the things given below. Write in a sequence—from the loudest to softest whistle. Wrapper of a toffee — A leaf — A balloon — The cap of a pen — Any other thing

Solution: This is an activity that requires personal experimentation. The loudness of the whistle depends on how you blow and the object used. A possible sequence from loudest to softest might be:

Balloon (can produce a loud, sharp sound)
Cap of a pen (can produce a clear whistle)
Leaf (depends on the type and how it's held, often a softer sound)
Wrapper of a toffee (usually makes a crinkling sound, not a distinct whistle, or a very soft one if manipulated correctly)

Other items like a blade of grass held taut between thumbs, or a straw can also be used to make whistles of varying loudness.

Common mistakes

Confusing the effect of blowing on cold hands versus hot food.
Not understanding that the temperature of the blown air depends on body temperature.
Difficulty in articulating the reason why air feels different at different distances.

Revision tips

Perform the experiments described in the chapter (blowing on hands, cooling food) to experience the concepts firsthand.
Discuss with family members how they use breath for warming or cooling.
Draw pictures illustrating different ways breath is used.
Focus on the 'why' behind each action – why does blowing cool hot things but warm cold hands?

Practice MCQs

Q1. When you blow on your cold hands, what is the effect of the air from your mouth?

Q2. Why does the air from your mouth feel less warm when you blow on your hands from a distance?

Q3. If you eat very hot potatoes without cooling them, what might happen?

Q4. Which of these is a way to cool hot food?

Q5. When Sonu blows on his cold hands, which is cooler?

Frequently asked questions

What is the main concept of Chapter 15, 'Blow Hot, Blow Cold'?

The chapter explores how the air we exhale can be used for both warming (like cold hands) and cooling (like hot food), depending on the situation and how we blow.

How does blowing on cold hands help?

When your hands are cold, the air from your mouth is warmer than the surrounding air and your hands. Blowing transfers this warmth to your hands, making them feel comfortable.

Why does blowing on hot food cool it down?

When you blow on hot food, you are essentially increasing the rate of evaporation and mixing cooler ambient air with the hot food, which helps to dissipate heat faster.

Does the distance from which you blow affect the temperature of the air?

Yes, if you blow from a distance, the air mixes more with the surrounding air and loses its warmth (or coolness) before reaching the object.

Can you give examples of other things we do by blowing air?

Yes, we blow to whistle, play musical instruments, clean dust off objects like spectacles, or even to make sounds with wrappers or leaves.

How do these NCERT Solutions help students?

These solutions provide clear, rewritten answers to all textbook questions, helping students understand the concepts of heat and temperature in a practical context and prepare for exams.

Content reviewed by the NCERT Help team. Editorial Team and update policy

NCERT Solutions PDF PDF on NCERT Help. URL unchanged for search indexing.