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5th Standard Samacheer kalvi Guide – Science Guide Air – Text Book Back Questions and Answers


I. Choose the correct answer:

Question 1.

Chlorofluorocarbon is used in

  1. a) refrigerator
  2. b) air conditioners
  3. c) Both a & b
  4. d) None

Answer:(c) Both a & b

Question 2.

Which of the following gas is released by automobiles?

  1. a) Carbon monoxide
  2. b) Oxygen
  3. c) Hydrogen
  4. d) Nitrogen

Answer:(a) Carbon monoxide

Question 3.

A wind mill is used to produce .

  1. a) chemical energy
  2. b) mechanical energy
  3. c) electric energy
  4. d) All of these

Answer:(c) electric energy


Question 4.

Influenza is caused by

  1. a) fungus
  2. b) bacteria
  3. c) virus
  4. d) protozoa

Answer:(c) virus

Question 5.

Height of mesosphere which lies after troposphere is

  1. a) 70 to 75km
  2. b) 75to 80 km
  3. c) 80 to 85 km
  4. d) 85to 90 km

Answer:(c) 80 to 85 km

II. Fill in the blanks:

Question 1.

Second highest layer of Earth’s atmosphere is _______.


Question 2.

Releasing substances like chemical compounds into the atmosphere is known as _______.

Answer:Air pollution

Question 3.

Airborne diseases can be caused by _______.


Question 4.

The _______ layer protects us from the harmful UV rays coming from the sun.



Question 5.

________ is used by plants as nitrates.


III. Match the following:

  1. Troposphere a. Satellite
  2. Stratosphere b. Ozone layer
  3. Exosphere c. Weather change
  4. Thermosphere d. Spacecraft
  5. Mesosphere e. Meteors


  1. Troposphere a. Weather change
  2. Stratosphere b. Ozone layer
  3. Exosphere c. Satellite
  4. Thermosphere d. Space craft
  5. Mesosphere e. Meteors

IV. Answer briefly:

Question 1.

What are the different layers of atmosphere?


  • Atmosphere is divided into five different layers.
  • The layers from the bottom upwards are called Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere.

Question 2.

What is air pollution?


The presence of harmful substances in the air which can have an adverse effect on living beings and the environment is called air pollution.


Question 3.

Name some of the airborne diseases.


Diphtheria, Whooping Cough, and Tuberculosis are some of the common airborne diseases caused by bacteria.

Question 4.

What is global warming?


  • Air pollution results in the accumulation of carbon dioxide in the atmosphere.
  • When gases like carbon dioxide are present in the atmosphere in a large amounts, they increase the atmospheric temperature.

Question 5.

Mention two ways of controlling air pollution.


  • Using public modes of transport can reduce the rate of pollution.
  • By reducing the usage of fossil fuels for burning.

V. Answer in detail:

Question 1.

List the importance of air.


  • Air is important for all living organisms.
  • Without air no life can exist on the Earth.
  • We take in oxygen from the air and release carbon dioxide. :
  • Plants in turn use carbon dioxide present in the air to produce their food.
  • The gases such as oxygen, nitrogen, carbon dioxide, and hydrogen present in the air are important to us for many reasons.

Water Cycle:

Water vapour present in the air is important for the formation of water cycle.

Supplies Energy:

  • We breathe oxygen present in the air and it is supplied to the cells in our body.
  • Body cells burn the food molecules with the help of oxygen and produce energy.

Sound travels through air:

Sound travels from the point of generation to the listener through air.

Useful for plants:

  • Nitrogen present in the air is useful for plants.
  • The nitrogen in the atmosphere is converted into easily absorbable nitrates by plants with the help of some microbes.


  • Movement of air is called wind.
  • This is helpful for the ships and boats to sail on the water. Airplanes and helicopters travel through air.


  • Paragliding and hang gliding are air sports and they are possible with the help of air.
  • Other sports like windsurfing, kite surfing, and sailing are also possible with the help of air.

Parachutes and Hot air balloons:

  • Parachutes and hot air balloons are used to land from above.
  • In case of emergency, people use parachutes and come down slowly and safely with the help of air.

Wind energy:

  • Air flows from a region of high pressure to low pressure.
  • This flow of air at high speed is called wind.
  • This wind is used to generate electric power with the help of windmills.

Question 2.

Explain any three airborne diseases.


Common cold:

  • Common cold is an infectious disease which affects the upper respiratory system like the nose and throat and it is easily spread.
  • Symptoms of the common cold include cough, painful throat, running nose, and sometimes fever.
  • Though many viruses can cause this, it is generally caused by Rhinovirus.


  • Influenza is commonly found during childhood.
  • It is caused by the virus, Myxo virus, and results in inflammation of nasal mucosa and pharynx.
  • It is also known as flu.


  • It is caused by Myxovirus parotitis and it affects the upper respiratory tract.
  • Some of the common symptoms of mumps include fever, headaches, sore throat, and swelling of parotid glands which makes jaw movement difficult.

VI. Higher-order Thinking Questions:

Question 1.

If there is no atmosphere, what will be the condition of Earth?


Without atmosphere means no life as there will be no oxygen which is essential for Earth’s organism to thrive on the planet Earth.

Question 2.

Give some suggestions to prevent air pollution.


  • Planting more trees can reduce the amount of carbon dioxide in the atmosphere.
  • Reduce the use of automobiles and use public transports.
  • Avoid aerosol spray products.


Activity 1.

Find out the places where wind energy is produced. Also, discuss about the importance of wind energy in the classroom and make a report on your discussion.


Tamil Nadu – First place in wind energy production.

Maharashtra – Second place in wind energy production.

Gujarat – Third place in wind energy production.

Rajasthan, Karnataka, Madhya Pradesh, Andhra Pradesh, Telangana, Kerala, Odisha, West Bengal, Jammu and Kashmir are the states producing wind power energy in India.


Importance of wind energy:

  • Wind energy is a source of renewable energy.
  • It does not contaminate.
  • It is inexhaustible and reduces the use of fossil fuels.
  • Wind energy does not generate waste and contaminated water.

Activity 2.

Find out the common air pollutants present in your area. Discuss about the effects of these pollutants. Record your observation in your notebook.



Common air pollutants


Carbon Monoxide

It is harmful to the body and inhibits the blood’s ability to deliver oxygen to the organs.

Sulfur Dioxide

It is extremely harmful to the respiratory system, causing asthma.

Nitrogen oxides

Causing respiratory distress and a number of other health issues.

Samacheer Kalvi 5th Science Guide Air Additional Questions and Answers

I. Choose the correct answer:

Question 1.

Atmosphere is composed of________ nitrogen.

(a) 68%

(b) 78%

(c) 58%


Answer:(b) 78%

Question 2.

Atmosphere is divided into _______ different layers.

(a) 5

(b) 4

(c) 6

(d) 3

Answer:(a) 5

Question 3.

__________ is the lowest layer of the atmosphere.

(a) Troposphere

(b) Stratosphere

(c) Mesosphere

(d) Exosphere

Answer:(a) Troposphere

Question 4.

Nitrogen fixation occur in ______.

(a) Humans

(b) animals

(c) plants

(d) All the above

Answer:(c) plants

Question 5.

__________ is an air sport.

(a) Paragliding

(b) Hang gliding

(c) both a & b

(d) None of these

Answer:(c) both a & b

II. Fill in the blanks:

Question 1.

_______ is known as paragliding capital of India.

Answer:Himachal Pradesh

Question 2.

The movement of air is called ______.Answer:wind

Question 3.

________ found above the mesosphere.Answer:Thermosphere

Question 4.

The word pollution is derived from the Latin word ______.Answer:Polluere

Question 5.

Extraction of minerals from the Earth is ______.Answer:Mining

III. Say True or False. If false, correct the statement:

Question 1.

World Tuberculosis Day is observed on 24th March.Answer:True

Question 2.

Causative organism of Tuberculosis is Cornebacterium.Answer:False

Correct statement:

Causative organism of Tuberculosis is Mycobacterium.

Question 3.

Influenza is commonly found in adults.Answer:False

Correct statement:

Influenza is commonly found in childhood.

Question 4.

Mumps affects the upper respiratory tract.Answer:True

Question 5.

Air pollutants cause pneumonia.Answer:True

IV. Match the following:

  1. Acid rain a. Bordetalla pertusis
  2. Eutrophication b. Airborne disease
  3. Diphtheria c. Green algae
  4. Whooping cough d. Nitrogen oxides



  1. d
  2. c
  3. b
  4. a

V. Answer briefly:

Question 1.

What is mesosphere?


  • The region above the stratosphere is called the mesosphere.
  • It extends upward to a height of about 85km from the ground.
  • The temperature in this layer decreases with height and it is -1100 C.

Question 2.

What is wind?


  • Air flows from a region of high pressure to low pressure.
  • This flow of air at high speed is called wind.

Question 3.

Why do plants need nitrogen?


  • Nitrogen present in the air is useful for plants.
  • The nitrogen in the atmosphere is converted into easily absorbable nitrates by plants with the help of some microbes.
  • It is known as nitrogen fixation. These nitrates are useful for the growth of plants.

Question 4.

Write a short note on chickenpox.


  • It is common among children but adults also may get it.
  • Affected people will have blisters or spots in the body and face along with fever.
  • Those blisters with fluid will drain but sometimes it may leave scars.

Question 5.

Why mountain climbers carry oxygen while climbing?


As the height increases, the amount of air in the atmosphere decreases and so the oxygen level will decrease.

That is why mountain climbers carry oxygen cylinders while climbing mountains.

Question 6.

How is acid rain formed?


  • Harmful gases like nitrogen oxides and sulfur oxides are released into the atmosphere while burning fossil fuels.
  • When it rains, the water droplets combine with these gases and fall on the ground in the form of acid rain.

VI. Answer in detail:

Question 1.

How can we prevent airborne disease?


  • Avoid close contact with people who have active symptoms of disease.
  • Maintain personal hygiene.
  • Keep the patient in complete isolation.
  • Cover nose and mouth while sneezing or coughing.
  • Avoid touching the face or other people with unwashed hands.
  • Wash your hands thoroughly.
  • Timely vaccination can prevent the diseases.

Question 2.

What are the common diseases caused by bacteria?


Diphtheria, Whooping Cough, and Tuberculosis are some of the common airborne diseases caused by bacteria.


  • It is caused by bacteria, Corynebacterium diphtheria.
  • It generally affects the upper respiratory tract (nose and throat) and causes fever, sore throat, and choking of air passage.

Whooping Cough:


  • Whooping cough is caused by Bordetalla pertusis.
  • It also affects the respiratory tract and causes mild fever, severe cough ending in a whoop.


  • Tuberculosis is caused by the bacteria, Microbacterium tuberculosis.
  • When we breathe, the bacteria present in the air gets into the lungs and affect it.
  • Infected person has to be treatedwith anti-tubercular drugs for a period of 6 months to one year.

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