Samacheer Kalvi Class 5 Science Solutions Term 3 Chapter 3 Air

Tamilnadu Samacheer Kalvi 5th Science Solutions Term 3 Chapter 3 Air

Samacheer Kalvi 5th Science Guide Air Text Book Back Questions and Answers

Evaluation

I. Choose the correct answer:

 

Question 1. Chlorofluorocarbon is used in
(a) refrigerator
(b) air conditioners
(c) Both a & b
(d) None
Answer: (c) Both a & b
In simple words: Chlorofluorocarbons, or CFCs, are chemicals found in both refrigerators and air conditioners. These chemicals help these machines cool things down.

🎯 Exam Tip: Remember that CFCs are harmful to the Earth's ozone layer, so their use has been largely phased out in new appliances.

 

Question 2. Which of the following gas is released by automobiles?
(a) Carbon monoxide
(b) Oxygen
(c) Hydrogen
(d) Nitrogen
Answer: (a) Carbon monoxide
In simple words: Cars release a gas called carbon monoxide. This gas is harmful and comes out from the exhaust pipes.

🎯 Exam Tip: Focus on understanding how different human activities contribute to air pollution and the specific pollutants released.

 

Question 3. A wind mill is used to produce .
(a) chemical energy
(b) mechanical energy
(c) electric energy
(d) All of the options
Answer: (c) electric energy
In simple words: Windmills use the wind's power to make electricity. They spin blades that turn a generator, creating clean energy.

🎯 Exam Tip: Distinguish between different types of energy conversion, noting that windmills convert wind's kinetic energy into electrical energy.

 

Question 4. Influenza is caused by
(a) fungus
(b) bacteria
(c) virus
(d) protozoa
Answer: (c) virus
In simple words: Influenza, also known as the flu, is caused by tiny living things called viruses. These viruses spread easily from person to person.

🎯 Exam Tip: Classify common diseases by their causative agents (virus, bacteria, fungus, protozoa) to answer such questions accurately.

 

Question 5. Height of mesosphere which lies after troposphere is
(a) 70 to 75km
(b) 75to 80 km
(c) 80 to 85 km
(d) 85to 90 km
Answer: (c) 80 to 85 km
In simple words: The mesosphere is a layer of Earth's atmosphere found above the stratosphere. It stretches from about 80 to 85 kilometers above the ground.

🎯 Exam Tip: Memorize the order and approximate heights of the different layers of Earth's atmosphere, as this is a common factual question.

II. Fill in the blanks:

 

Question 1. Second highest layer of Earth's atmosphere is ______.
Answer: Thermosphere
In simple words: The thermosphere is the second-highest layer of our planet's atmosphere. It is located above the mesosphere and below the exosphere.

🎯 Exam Tip: Learn the sequence of atmospheric layers, usually starting from the surface: troposphere, stratosphere, mesosphere, thermosphere, exosphere.

 

Question 2. Releasing substances like chemical compounds into the atmosphere is known as ______.
Answer: Air pollution
In simple words: When harmful things like chemicals are put into the air, it is called air pollution. This makes the air dirty and unsafe.

🎯 Exam Tip: Define air pollution clearly, including specific examples of pollutants and their sources.

 

Question 3. Airborne diseases can be caused by ______.
Answer: Microorganisms
In simple words: Tiny living things, called microorganisms, can cause diseases that spread through the air. These include viruses and bacteria.

🎯 Exam Tip: Understand that microorganisms (like viruses and bacteria) are the primary cause of airborne diseases.

 

Question 4. The ______ layer protects us from the harmful UV rays coming from the sun.
Answer: Ozone
In simple words: The ozone layer acts like a shield high in the sky. It stops most of the sun's bad UV rays from reaching us.

🎯 Exam Tip: Know the role of the ozone layer in the stratosphere and its importance for protecting life on Earth from harmful radiation.

 

Question 5. ______ is used by plants as nitrates.
Answer: Nitrogen
In simple words: Plants need nitrogen to grow well. They get this nitrogen from the soil in a form called nitrates.

🎯 Exam Tip: Recall the importance of nitrogen for plant growth and its conversion into nitrates through the nitrogen cycle.

III. Match the following:

 

Question. Match the following terms with their descriptions.

Answer:
1. Troposphere - a. Weather change
2. Stratosphere - b. Ozone layer
3. Exosphere - c. Satellite
4. Thermosphere - d. Spacecraft
5. Mesosphere - e. Meteors
In simple words: Each layer of the atmosphere has special features. The troposphere is where weather happens, the stratosphere holds the ozone layer, the exosphere is where satellites orbit, the thermosphere is visited by spacecraft, and the mesosphere burns up meteors.

🎯 Exam Tip: When matching, carefully connect each item to its most characteristic feature or function. Review the unique properties of each atmospheric layer.

IV. Answer briefly:

 

Question 1. What are the different layers of atmosphere?
Answer: The Earth's atmosphere is divided into five main layers. From the bottom up, these layers are called the Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. Each layer has different characteristics and plays a unique role in protecting our planet.
In simple words: Our Earth's air is like an onion with five layers. They are Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere, starting from the ground and going up.

🎯 Exam Tip: List the layers in their correct ascending or descending order and briefly mention one key characteristic of each for a comprehensive answer.

 

Question 2. What is air pollution?
Answer: Air pollution happens when harmful substances enter the air. These substances can negatively affect all living things and the environment around us. This makes the air unhealthy to breathe and damages nature.
In simple words: Air pollution is when bad things like chemicals get into the air, making it dirty and harmful for people, animals, and the Earth.

🎯 Exam Tip: Define air pollution by focusing on "harmful substances" and their "adverse effects" on "living beings and the environment."

 

Question 3. Name some of the airborne diseases.
Answer: Some common airborne diseases that are caused by bacteria include Diphtheria, Whooping Cough, and Tuberculosis. These illnesses can spread through tiny droplets in the air.
In simple words: Some sicknesses that spread through the air are Diphtheria, Whooping Cough, and Tuberculosis.

🎯 Exam Tip: When listing diseases, try to include at least two to three examples for full marks.

 

Question 4. What is global warming?
Answer: Global warming occurs when carbon dioxide and other gases build up in the atmosphere due to air pollution. When these gases are present in large amounts, they trap heat and cause the Earth's atmospheric temperature to rise. This trapped heat leads to an overall warming of the planet.
In simple words: Global warming is when the Earth gets hotter because too much carbon dioxide and other gases trap heat in the air. This happens because of pollution.

🎯 Exam Tip: Clearly link global warming to the accumulation of greenhouse gases (like carbon dioxide) and the subsequent increase in atmospheric temperature.

 

Question 5. Mention two ways of controlling air pollution.
Answer: Two effective ways to control air pollution are:
1. Using public modes of transport more often can reduce the amount of pollution caused by individual vehicles.
2. Reducing the usage of fossil fuels for burning, as these release harmful gases into the atmosphere. Choosing cleaner energy sources can greatly help.
In simple words: We can stop air pollution by using public buses or trains more and by burning less fuel like petrol or diesel.

🎯 Exam Tip: When suggesting solutions, provide specific and practical actions, and remember to offer at least the number of points requested in the question (e.g., "two ways").

V. Answer in detail:

 

Question 1. List the importance of air.
Answer: Air is essential for many reasons:
- Air is very important for all living organisms to survive.
- No life can exist on Earth without air.
- We breathe in oxygen from the air and release carbon dioxide.
- Plants use carbon dioxide from the air to make their own food. This process is called photosynthesis.
- Important gases like oxygen, nitrogen, carbon dioxide, and hydrogen are all present in the air and are needed for many different reasons.
Water Cycle: Water vapor in the air helps form clouds and makes the water cycle happen.
Supplies Energy: We breathe oxygen, which then goes to our cells. Our body cells use oxygen to burn food molecules and create energy.
Sound travels through air: Sound needs air to travel from where it is made to a listener's ears.
Useful for plants: Nitrogen in the air is good for plants. Microbes in the soil help change atmospheric nitrogen into nitrates, which plants can easily absorb.
Transport: The movement of air is called wind. Wind helps ships and boats move on water. Airplanes and helicopters also fly through the air. Wind energy is a clean source of power.
Sports: Many air sports, like paragliding and hang gliding, are possible because of air. Other sports such as windsurfing, kite surfing, and sailing also depend on air.
Parachutes and Hot air balloons: Parachutes and hot air balloons are used to land safely from heights. In emergencies, parachutes help people come down slowly and safely.
Wind energy: Air moves from high pressure to low pressure, creating wind. This fast-moving wind can be used to generate electricity with the help of windmills.
In simple words: Air is vital for all life, helping us breathe, plants grow, and even sound travel. It also powers wind energy, helps transport, and makes many sports possible.

🎯 Exam Tip: When listing importance, categorize the points (e.g., for living organisms, water cycle, energy, transport, sports) to ensure a comprehensive and well-structured answer.

 

Question 2. Explain any three airborne diseases.
Answer: Here are three common airborne diseases:
1. Common cold: This is an infectious disease that affects the upper respiratory system, including the nose and throat. It spreads easily and common symptoms are cough, sore throat, runny nose, and sometimes fever. It is mostly caused by the Rhinovirus.
2. Influenza: Also known as the flu, influenza is often seen in childhood. It is caused by the Myxo virus, which leads to swelling and inflammation in the nose and throat area. It's also generally referred to as flu.
3. Mumps: Mumps is caused by the Myxovirus parotitis. It affects the upper respiratory tract. Common symptoms include fever, headaches, sore throat, and swollen parotid glands, which can make it hard to move the jaw. Many airborne diseases are highly contagious, highlighting the importance of good hygiene.
In simple words: Three common sicknesses that spread through the air are the common cold (makes your nose run and throat sore), influenza (the flu, also makes your nose and throat sore), and mumps (causes fever, headaches, and swollen neck glands).

🎯 Exam Tip: For each disease, mention its causative agent (if known), the affected body part, and a few key symptoms for a complete explanation.

VI. Higher-order Thinking Questions:

 

Question 1. If there is no atmosphere, what will be the condition of Earth?
Answer: If Earth had no atmosphere, there would be no life on the planet. This is because oxygen, which is vital for almost all living organisms, would not be present. The atmosphere also protects Earth from harmful radiation and extreme temperature changes, which are crucial for sustaining life. Without these protections, the Earth would be a barren and lifeless place, much like the moon.
In simple words: Without air around Earth, nothing could live here because there would be no oxygen to breathe. The Earth would also be very cold or very hot, and dangerous rays from the sun would hit it.

🎯 Exam Tip: Beyond just oxygen, also consider the atmosphere's roles in temperature regulation, protection from radiation, and the water cycle when explaining its importance.

 

Question 2. Give some suggestions to prevent air pollution.
Answer: Here are some suggestions to prevent air pollution:
1. Planting more trees can help reduce the amount of carbon dioxide in the atmosphere, as trees absorb this gas.
2. Reducing the use of private cars and using public transportation, like buses or trains, can lower vehicle emissions.
3. Avoiding aerosol spray products, which can release harmful chemicals into the air. These actions help keep our air clean and healthy.
In simple words: To stop air pollution, we should plant more trees, use public transport more often, and try not to use spray cans.

🎯 Exam Tip: Provide practical and diverse solutions that address different sources of air pollution, such as vehicles, industrial processes, and household products.

Activities

 

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.
Answer: In India, several states are leading in wind energy production:
- Tamil Nadu is the first place in wind energy production.
- Maharashtra is the second place.
- Gujarat is the third place.
Other states that produce wind power energy include Rajasthan, Karnataka, Madhya Pradesh, Andhra Pradesh, Telangana, Kerala, Odisha, West Bengal, and Jammu and Kashmir.
Importance of wind energy:
- Wind energy is a source of renewable energy, meaning it will not run out.
- It does not pollute the air or water.
- It is inexhaustible and helps reduce the need to use fossil fuels, which are harmful.
- Wind energy production does not create waste or contaminated water. It's a clean and sustainable way to generate power.
In simple words: Many places in India, like Tamil Nadu and Maharashtra, make energy from wind. Wind energy is good because it never ends, does not make the air dirty, and does not create trash or bad water.

🎯 Exam Tip: When discussing renewable energy, highlight its key benefits such as being inexhaustible, non-polluting, and reducing reliance on fossil fuels.

 

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.
Answer: Here are some common air pollutants and their effects:

These pollutants can have serious impacts on human health and the environment.
In simple words: Common air pollutants like carbon monoxide stop our blood from carrying oxygen, sulfur dioxide makes it hard to breathe and can cause asthma, and nitrogen oxides cause breathing problems and other sicknesses.

🎯 Exam Tip: Remember to name specific pollutants and accurately describe their corresponding health or environmental effects.

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%
(d) 21%
Answer: (b) 78%
In simple words: The air around Earth is mostly made of nitrogen gas, which makes up about 78% of the atmosphere.

🎯 Exam Tip: Recall the major components of the atmosphere and their approximate percentages to answer questions about atmospheric composition.

 

Question 2. Atmosphere is divided into ______ different layers.
(a) 5
(b) 4
(c) 6
(d) 3
Answer: (a) 5
In simple words: The Earth's atmosphere is split into five main layers, each with its own characteristics.

🎯 Exam Tip: Be precise about the number of atmospheric layers; remember the standard count is five.

 

Question 3. ______ is the lowest layer of the atmosphere.
(a) Troposphere
(b) Stratosphere
(c) Mesosphere
(d) Exosphere
Answer: (a) Troposphere
In simple words: The troposphere is the layer of air closest to the Earth's surface. This is where we live and where most weather happens.

🎯 Exam Tip: Identify the troposphere as the bottom-most layer, which is crucial for understanding weather patterns.

 

Question 4. Nitrogen fixation occur in ______ .
(a) Humans
(b) animals
(c) plants
(d) All of the options
Answer: (c) plants
In simple words: Nitrogen fixation is a process where nitrogen gas from the air is changed into a form that plants can use. This helps plants grow.

🎯 Exam Tip: Understand that nitrogen fixation is a biological process primarily associated with certain bacteria that interact with plants.

 

Question 5. ______ is an air sport.
(a) Paragliding
(b) Hang gliding
(c) both a & b
(d) None of the options
Answer: (c) both a & b
In simple words: Both paragliding and hang gliding are sports where people fly through the air using special equipment. They use air currents to stay aloft.

🎯 Exam Tip: Be familiar with examples of air sports that utilize air currents and equipment for flight.

II. Fill in the blanks:

 

Question 1. ______ is known as paragliding capital of India.
Answer: Himachal Pradesh
In simple words: Himachal Pradesh is a state in India famous for paragliding, making it known as the paragliding capital.

🎯 Exam Tip: Remember geographical facts related to sports or specific natural phenomena.

 

Question 2. The movement of air is called ______.
Answer: wind
In simple words: When air moves from one place to another, we call it wind.

🎯 Exam Tip: Use precise scientific terms for natural phenomena; 'wind' specifically describes moving air.

 

Question 3. ______ found above the mesosphere.
Answer: Thermosphere
In simple words: The thermosphere is the layer of air that is located directly above the mesosphere.

🎯 Exam Tip: Recall the correct order of atmospheric layers to identify which one comes after the mesosphere.

 

Question 4. The word pollution is derived from the Latin word ______.
Answer: Polluere
In simple words: The English word 'pollution' comes from the old Latin word 'Polluere', which means to soil or defile.

🎯 Exam Tip: Knowing the etymology of scientific terms can sometimes help in understanding their meaning.

 

Question 5. Extraction of minerals from the Earth is ______.
Answer: Mining
In simple words: The process of digging out minerals from inside the Earth is called mining.

🎯 Exam Tip: Define key geological and environmental terms clearly.

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

 

Question 1. World Tuberculosis Day is observed on 24th March.
Answer: True
In simple words: World Tuberculosis Day is indeed celebrated every year on March 24th. This day helps to raise awareness about tuberculosis.

🎯 Exam Tip: Memorize important dates related to health awareness or environmental events as they can appear in general knowledge questions.

 

Question 2. Causative organism of Tuberculosis is Cornebacterium.
Answer: False
Correct statement: Causative organism of Tuberculosis is Mycobacterium.
In simple words: This statement is false because Tuberculosis is caused by a type of bacteria called Mycobacterium, not Cornebacterium.

🎯 Exam Tip: Always identify the correct causative agent for diseases, especially when a false statement requires correction.

 

Question 3. Influenza is commonly found in adults.
Answer: False
Correct statement: Influenza is commonly found in childhood.
In simple words: This statement is false. Influenza, or the flu, is actually very common among children.

🎯 Exam Tip: Pay attention to the age groups most affected by common diseases, as this can be a key detail for true/false questions.

 

Question 4. Mumps affects the upper respiratory tract.
Answer: True
In simple words: It is true that mumps affects the upper breathing areas. It also causes swelling in the glands.

🎯 Exam Tip: Know the specific body systems or parts affected by different diseases for accurate answers.

 

Question 5. Air pollutants cause pneumonia.
Answer: True
In simple words: It is true that air pollutants can lead to diseases like pneumonia because they harm the lungs.

🎯 Exam Tip: Recognize the direct links between environmental factors (like air pollution) and respiratory health issues (like pneumonia).

IV. Match the following:

 

Question. Match the following.

Answer:
1. d (Acid rain - Nitrogen oxides)
2. c (Eutrophication - Green algae)
3. b (Diphtheria - Airborne disease)
4. a (Whooping cough - Bordetalla pertusis)
In simple words: Acid rain is caused by gases like nitrogen oxides. Eutrophication leads to lots of green algae. Diphtheria is a sickness that spreads through the air. Whooping cough is caused by a bacteria called Bordetalla pertusis.

🎯 Exam Tip: For matching questions, understand the direct cause or effect relationship between each item to link them correctly, especially in science and health topics.

V. Answer Briefly:

 

Question 1. What is mesosphere?
Answer: The mesosphere is the layer of Earth's atmosphere found directly above the stratosphere. It stretches upwards to a height of about 85 kilometers from the Earth's surface. In this particular layer, the air becomes progressively colder as altitude increases, with temperatures dropping to as low as -110 degrees Celsius. The mesosphere is also where most meteors burn up when they enter Earth's atmosphere, creating visible shooting stars.
In simple words: The mesosphere is the atmosphere layer above the stratosphere, reaching about 85 km high. It gets very cold there.

🎯 Exam Tip: Remember the main characteristic of the mesosphere is that it is the coldest layer of the atmosphere and where meteors disintegrate.

 

Question 2. What is wind?
Answer: Wind is the natural movement of air across the Earth's surface. It occurs when air flows from an area of higher air pressure towards an area of lower air pressure. This movement of air, especially when it is at a high speed, is what we commonly refer to as wind. Wind is a type of kinetic energy, which humans have learned to harness using windmills and wind turbines for power generation.
In simple words: Wind is air moving fast. It moves from places with high air pressure to places with low air pressure.

🎯 Exam Tip: When defining wind, always mention the key concept of air moving from high pressure to low pressure areas.

 

Question 3. Why do plants need nitrogen?
Answer: Plants need nitrogen, which is abundant in the air, to ensure their healthy growth and development. Tiny living organisms in the soil, known as microbes, play a crucial role in changing this atmospheric nitrogen into a form called nitrates, which plants can easily absorb. This important conversion process is called nitrogen fixation, and these nitrates are absolutely essential for the overall growth of plants, helping them build proteins and other vital components. Nitrogen is a key part of chlorophyll, which plants use to make their food through photosynthesis, giving them their green color.
In simple words: Plants need nitrogen from the air to grow well. Microbes in the soil help turn nitrogen into nitrates that plants can use.

🎯 Exam Tip: Highlight "nitrogen fixation" and the role of "microbes" and "nitrates" as key terms when explaining how plants get and use nitrogen.

 

Question 4. Write a short note on chickenpox.
Answer: Chickenpox is a widespread illness that primarily affects children, but adults can also contract it. Individuals suffering from chickenpox develop characteristic itchy blisters or red spots all over their body and face, usually accompanied by a fever. These fluid-filled blisters eventually dry up and scab over, though they can sometimes leave small scars on the skin. Chickenpox is caused by the varicella-zoster virus and is very contagious, spreading easily from person to person.
In simple words: Chickenpox causes spots and fever, mostly in kids but also adults. The spots dry up but might leave scars.

🎯 Exam Tip: Mentioning the characteristic blisters, fever, and its common occurrence in children are essential points for describing chickenpox.

 

Question 5. Why mountain climbers carry oxygen while climbing?
Answer: As mountain climbers ascend to greater heights, the air in the atmosphere becomes noticeably thinner. This reduction in air density means that there is significantly less oxygen available for breathing at higher altitudes. Therefore, mountain climbers carry portable oxygen cylinders with them to ensure they have a sufficient supply of oxygen to breathe comfortably and safely. Without supplemental oxygen, climbers can suffer from altitude sickness, which can be very serious and life-threatening.
In simple words: Mountain climbers carry oxygen because the higher they go, the thinner the air gets, meaning less oxygen to breathe.

🎯 Exam Tip: The key points are "thinner air" and "less oxygen" at higher altitudes, which necessitates carrying oxygen cylinders.

 

Question 6. How is acid rain formed?
Answer: Acid rain forms primarily when industrial activities and vehicle emissions release harmful gases, specifically nitrogen oxides and sulfur oxides, into the atmosphere from burning fossil fuels. These pollutant gases then mix with water droplets, oxygen, and other chemicals in the clouds. When precipitation occurs, this contaminated water falls to the Earth as acid rain, which can cause significant damage to the environment, including plants, aquatic life, and even man-made structures. Acid rain damages forests and aquatic life by making soil and water more acidic, impacting entire ecosystems.
In simple words: Acid rain forms when harmful gases like nitrogen and sulfur oxides from burning fossil fuels mix with water in the air and fall as rain.

🎯 Exam Tip: Focus on the specific gases (nitrogen oxides, sulfur oxides) and their source (burning fossil fuels) as the main causes of acid rain.

VI. Answer in Detail:

 

Question 1. How can we prevent airborne disease?
Answer: Preventing airborne diseases involves several key practices to limit the spread of germs. Firstly, it is important to avoid close contact with individuals who are showing active symptoms of an illness. Maintaining excellent personal hygiene, such as regular handwashing, is crucial. If someone is sick, keeping them in complete isolation helps prevent the infection from spreading to others. Always cover your nose and mouth thoroughly when you sneeze or cough to contain respiratory droplets. You should also avoid touching your face and other people with unwashed hands. Thoroughly washing your hands with soap and water for at least 20 seconds is very effective. Lastly, ensuring timely vaccination can provide protection against many preventable diseases. Airborne diseases spread through tiny droplets in the air, making these preventative measures crucial in crowded spaces.
In simple words: To prevent airborne diseases, avoid sick people, practice good hygiene, isolate patients, cover coughs/sneezes, wash hands well, and get vaccinated.

🎯 Exam Tip: When listing prevention methods, ensure a range of actions from personal hygiene to community measures like vaccination and isolation are included.

 

Question 2. What are the common diseases caused by bacteria?
Answer: Several common illnesses are caused by bacteria, including Diphtheria, Whooping Cough, and Tuberculosis.
**Diphtheria:** This disease is caused by the bacterium *Corynebacterium diphtheria*. It primarily affects the upper respiratory tract, involving the nose and throat, and leads to symptoms such as fever, a sore throat, and difficulty breathing due to blocked air passages.
**Whooping Cough:** Also known as pertussis, Whooping Cough is caused by the bacterium *Bordetella pertussis*. It affects the respiratory system, causing a mild fever and a characteristic severe cough that often ends with a "whooping" sound as the person breathes in.
**Tuberculosis (TB):** This serious disease is caused by the bacterium *Mycobacterium tuberculosis*. When a person breathes, these bacteria can enter the lungs and cause infection. Infected individuals need to undergo a long course of anti-tubercular drugs, typically for a period of 6 months to one year, to recover fully. Vaccinations are available for some bacterial diseases like Diphtheria and Whooping Cough, which have significantly reduced their spread.
In simple words: Common diseases caused by bacteria include Diphtheria, Whooping Cough, and Tuberculosis. Diphtheria affects the throat, Whooping Cough causes bad coughing, and TB harms the lungs.

🎯 Exam Tip: For each disease, clearly state the name of the disease, the causative bacterium, and its main symptoms or affected body parts.