Blow Hot, Blow Cold - 2 Class 5 Worksheet EVS Chapter 15

Q1: Fill in the Banks.

(i) Our breath is ______than a hot chapatti hence we can make it cool by blowing on it.
Ans: colder

(ii) Whenever the air flows ___ the paper snake will move in the clockwise direction.
Ans: upwards

(iii) The ___ air rises up while the ____ air comes down.
Ans: hot, cold

(iv) The air blown from our mouth is ____ in winter and _____ in summer.
Ans: hot, cold

(v) The air we breathe out contains _____ which turns into drops when they touch a cold surface.
Ans: water vapours

(vi) We can ____ our hands in winter by blowing from our mouth.
Ans: warm

(vii) When we fan a burning coal we will increase the ____ of the coal.
Ans: fire

(viii) When we breathe in our chest ______.
Ans: comes out

(ix)  _____ air is light and rises up.
Ans: warm

(x) Our breath is ____ than hot tea and hence we blow to cool it.
Ans: colder

Q2: Give one or two words for the following.

(i) Instrument that is used to listen to heartbeat._____
Ans: Stethoscope

(ii)  How many times does our heart beat in one minute?
Ans: 73 times

(iii) When the air flows downward the paper snake will move________.
Ans: anti clockwise

Q3: True & False Questions

(i) A wood cutter kept blowing into his hands while cutting the wood to keep them cold.
Ans: False

(ii) A popcorn seller fans the burning coal to increase the air supply.
Ans: True

(iii) We use a thermometer to listen to the heart beat.
Ans: False

(iv) Whenever the air flows upward, the paper snake will move clockwise.
Ans: True

(v) The story Blow Hot Blow Cold was written by Dr. Zakir Hussain, the former president of India.
Ans: True

Q4: Answer the given questions

(i) Suppose you are given hot khichdi to eat. How will it cool down without blowing air from your mouth?
Ans: The khichdi will cool down:

• By spreading in a big plate.
• By keeping it under the fan.

(ii) You bang your head while playing and your forehead Is swollen. A warm handkerchief is put over the swollen area it gives you relief. Why it is so?
Ans: Warm air soothes the skin giving relief.

(iii) Why the air blown from our mouth cools the things in summer and warm in winters?
Ans: The air blown from our mouth is always at our normal body temperature which is 98.70C. So when we blow at some colder thing in winter its temperature rises and if we blow at some hotter thing its temperature falls.

(iv) Why do the people blow on the spectacles before cleaning it?
Ans: When we blow on spectacles water vapours will come out and the glass will become haze. It will make the cleaning of the spectacles easy and smooth.

(v) How do you cool down your porridge without blowing air from your mouth?
Ans: We can cool down porridge:

• By pouring it in an open bowl.
• By putting it under the fan.
• By blowing air from the mouth.

(vi) How does the mirror look hazy when we blow hard on it?
Ans: When we blow hard, some water vapours also come out with the breath and falls on the mirror. These water vapours make the mirror hazy.

(vii) Why does our heart beat faster after running?
Ans: When we run or jump our blood circulation increases. Our heart has to do more work to pump the blood faster. So it beats faster.

(viii) How does breath help to warm your cold hands winter?
Ans: The air that we blow from the mouth is hot in the winter. So when we blow on our hand it makes them warm.