Atmosphere - Structure and Composition MCQ Quiz - Objective Question with Answer for Atmosphere - Structure and Composition - Download Free PDF

The correct answer is Stratosphere.

Key Points

• Stratosphere
  • The stratosphere starts just above the troposphere and extends to 50 kilometres high.
  • The ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer.
  • The maximum concentration of ozone is found in Stratosphere.
• ​Hence option 3 is correct.

Additional Information

• The different layers of the atmosphere are listed below:
  • Exosphere
    • This is the upper limit of our atmosphere.
    • It extends from the top of the thermosphere up to 10,000 km (6,200 mi).
  • Thermosphere
    • The thermosphere starts just above the mesosphere and extends to 600 kilometres (372 miles) high.
    • Aurora and satellites occur in this layer.
  • Mesosphere
    • The mesosphere starts just above the stratosphere and extends to 85 kilometres (53 miles) high.
    • Meteors burn up in this layer.
  • Troposphere
    • The troposphere is the lowest layer of the Earth's atmosphere.
    • The air is very well mixed and the temperature decreases with an increase in altitude.
    • The air in the troposphere is heated from the ground up.
    • The surface of the Earth absorbs energy and heats up faster than the air does.
  • Ionosphere
    • The ionosphere is an abundant layer of electrons and ionized atoms and molecules that stretches from about 48 kilometres.
    • The ionosphere is a critical link in the chain of Sun-Earth interactions.
    • This region is what makes radio communications possible.

The correct answer is Stratosphere.

Key Points

• Stratosphere
  • The stratosphere starts just above the troposphere and extends to 50 kilometres high.
  • The ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer.
  • The maximum concentration of ozone is found in Stratosphere.
• ​Hence option 3 is correct.

Additional Information

• The different layers of the atmosphere are listed below:
  • Exosphere
    • This is the upper limit of our atmosphere.
    • It extends from the top of the thermosphere up to 10,000 km (6,200 mi).
  • Thermosphere
    • The thermosphere starts just above the mesosphere and extends to 600 kilometres (372 miles) high.
    • Aurora and satellites occur in this layer.
  • Mesosphere
    • The mesosphere starts just above the stratosphere and extends to 85 kilometres (53 miles) high.
    • Meteors burn up in this layer.
  • Troposphere
    • The troposphere is the lowest layer of the Earth's atmosphere.
    • The air is very well mixed and the temperature decreases with an increase in altitude.
    • The air in the troposphere is heated from the ground up.
    • The surface of the Earth absorbs energy and heats up faster than the air does.
  • Ionosphere
    • The ionosphere is an abundant layer of electrons and ionized atoms and molecules that stretches from about 48 kilometres.
    • The ionosphere is a critical link in the chain of Sun-Earth interactions.
    • This region is what makes radio communications possible.

The correct answer is Stratosphere.

Key PointsOzone layer

• The ozone layer is a natural layer of gas in the upper atmosphere that protects humans and other living things from harmful ultraviolet (UV) radiation from the sun.
• The ozone layer exists in the stratosphere, a layer 10 to 50 km above the Earth’s surface.
• The international community established the Montreal Protocol on ozone-depleting substances in 1987, to address the destruction of the ozone layer.
• The stratospheric ozone layer absorbs ultraviolet (UV) radiation, preventing dangerous UV rays from hitting the Earth's surface and harming living organisms.
• It contains a high concentration of ozone (O₃) in relation to other parts of the atmosphere.
• The ozone layer in the stratosphere is affected by the increase in the atmospheric concentration of CFC (chlorofluorocarbons).
• In the atmosphere, CFCs drift slowly upward to the stratosphere, where they are broken up by ultraviolet radiation, releasing chlorine atoms, which can destroy ozone molecules.
• CFCs are the main reason for the Ozone hole.
• The other reasons for ozone depletion are a wide range of industrial and consumer applications, mainly refrigerators, air conditioners (hydrochlorofluorocarbons (HCFCs), and fire extinguishers.

The correct answer is Troposphere, Stratosphere, Mesosphere, Thermosphere.

Key Points

• The atmosphere is divided into layers based on temperature gradients, with the sequence being Troposphere, Stratosphere, Mesosphere, and Thermosphere as height increases.
• The Troposphere is the lowest layer, extending up to approximately 8-15 km, where most weather phenomena occur.
• The Stratosphere lies above the Troposphere, extending up to about 50 km, and contains the ozone layer that absorbs harmful UV radiation.
• The Mesosphere extends from 50 km to 85 km and is the layer where meteors burn upon entering Earth’s atmosphere.
• The Thermosphere, above the Mesosphere, extends up to 600 km and is characterized by high temperatures due to solar radiation absorption.

Additional Information

• Troposphere:
  • It contains approximately 75% of the atmosphere's mass.
  • Temperature decreases with altitude in this layer.
  • Most clouds and precipitation occur in the Troposphere.
• Stratosphere:
  • Temperature increases with altitude due to the presence of the ozone layer.
  • Commercial aircraft often cruise in this layer for smoother flights.
• Mesosphere:
  • It is the coldest atmospheric layer, with temperatures dropping as low as -90°C.
  • This layer protects Earth by burning up meteoroids.
• Thermosphere:
  • Temperatures can exceed 2000°C due to solar radiation absorption.
  • The International Space Station orbits within this layer.
• Exosphere:
  • It is the outermost layer of Earth's atmosphere, transitioning into space.
  • Particles in the Exosphere are sparse and move freely due to weak gravitational forces.

The correct answer is Stratosphere.

Key Points

• The ozone layer is located in the stratosphere, which is the second layer of Earth's atmosphere.
• The ozone layer lies approximately 15 to 35 kilometers above Earth's surface, with its maximum concentration between 20 and 30 kilometers.
• The ozone layer absorbs and blocks the majority of the Sun's harmful ultraviolet (UV) radiation, particularly UV-B and UV-C rays.
• The presence of the ozone layer is critical for protecting life on Earth, as excessive UV radiation can cause skin cancer, cataracts, and harm ecosystems.
• Human activities, particularly the use of chlorofluorocarbons (CFCs), have caused ozone depletion, leading to efforts like the Montreal Protocol to mitigate damage.

Additional Information

• Stratosphere:
  • The stratosphere is the layer of the atmosphere located above the troposphere and below the mesosphere, extending from approximately 10 km to 50 km above the Earth's surface.
  • Unlike the troposphere, the temperature in the stratosphere increases with altitude due to the absorption of solar radiation by ozone.
• Ozone (O₃):
  • Ozone is a molecule composed of three oxygen atoms and is a highly reactive gas.
  • It is created naturally in the atmosphere through the interaction of ultraviolet radiation with oxygen molecules (O₂).
• Ozone Depletion:
  • Ozone depletion refers to the thinning of the ozone layer caused by chemicals like chlorofluorocarbons (CFCs), halons, and other ozone-depleting substances (ODS).
  • The Antarctic ozone hole is a prominent example of ozone depletion, observed annually since the 1980s.
• Montreal Protocol:
  • The Montreal Protocol, signed in 1987, is an international treaty designed to phase out the production and consumption of ozone-depleting substances.
  • It has been widely successful, with significant recovery of the ozone layer projected by mid-21st century.
• Ultraviolet Radiation (UV Rays):
  • UV radiation is a type of electromagnetic radiation emitted by the Sun, categorized into UV-A, UV-B, and UV-C based on wavelength.
  • The ozone layer effectively absorbs UV-B and UV-C rays, while UV-A rays are less harmful and reach Earth's surface.

The correct answer is Thermosphere.

Key Points

The atmosphere consists of different layers with varying densities and temperatures. The column of the atmosphere is divided into five different layers depending upon the temperature condition.
They are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

• The troposphere
  • It is the lowest part of the Earth's atmosphere in which all tropical changes take place. It contains about 75% of the total air in the atmosphere.
  • This layer contains dust particles and water vapor.
  • All changes in climate and weather take place in this layer.
  • This is the most important layer for all biological activity.
  • The zone separating the troposphere from the stratosphere is known as the tropopause.
  • The temperature here is nearly constant, and hence, it is called tropopause.
• The stratosphere
  • It is found above the tropopause and extends up to a height of 50 km.
  • One important feature of the stratosphere is that it contains the ozone layer.
  • This layer absorbs ultraviolet radiation and shields life on the earth from an intense, harmful form of energy.
  • The stratopause caps the top of the stratosphere.
• The mesosphere
  • It lies above the stratosphere, which extends up to a height of 80 km.
  • In this layer, once again, the temperature starts decreasing with the increase in altitude and reaches up to minus 100°C at a height of 80 km.
  • The upper limit of the mesosphere is known as mesopause.
• The thermosphere 
  • It is located between 80 and 400 km above the mesopause.
  • It contains electrically charged particles known as ions, and hence, it is also known as the ionosphere.
  • Radio waves transmitted from the earth are reflected back to the earth by this layer.
  • It contains Ions and helps in wireless communication
• The temperature here starts increasing with height.
• The exosphere
  • It is the uppermost layer of the atmosphere.
  • This is the highest layer but very little is known about it.
  • Whatever contents are there, these are extremely rarefied in this layer, and it gradually merges with outer space.

​

The correct answer is thermosphere.

Key Points

• The thermosphere lies above the mesopause and is a region in which temperatures increase with height.
• Thermosphere:
  • In the thermosphere, the temperature rises very rapidly with increasing height.
  • The ionosphere is a part of this layer.
  • It extends between 80-400 km. This layer helps in radio transmission.

Additional Information

• There are a total of five atmospheric layers. These are -
  • Troposphere.
  • Stratosphere.
  • Mesosphere.
  • Thermosphere.
  • Ionosphere: the lowest part of the Thermosphere contains the ionosphere.
  • Exosphere.
• Stratosphere:
  • It lies beyond the troposphere, up to an altitude of 50 km from the earth's surface.
  • The temperature in this layer remains constant for some distance but then rises to reach a level of 0°C at 50 km altitude.
  • This rise is due to the presence of ozone.
  • This layer is almost free from clouds and associated weather phenomena, making conditions most ideal for flying aeroplanes.
• Exosphere:
  • This is the uppermost layer of the atmosphere extending beyond the ionosphere above a height of about 400 km.
  • The air is extremely rarefied and the temperature gradually increases through the layer.
  • Light gases like helium and hydrogen float into space from here.
• Troposphere:
  • It is the lowermost layer of the atmosphere.
  • The layer starts at Earth's surface and extends 8 to 14.5 km high (5 to 9 miles).
  • The troposphere contains dust particles and water vapour.
  • This is the most important layer of the atmosphere because all kinds of weather changes take place only in this layer.
  • The zone dividing troposphere from the stratosphere is known as the tropopause.

The correct answer is Troposphere

Key PointsTroposphere

• The troposphere is the lowest portion of Earth’s atmosphere and contains approximately 70% of the total air in the atmosphere’s mass and 99% of its water vapour and aerosols. Hence statement 4 is correct.
• The average depth of the troposphere is approximately 17 km in the middle latitudes.
• The characteristic features of the Troposphere are its great density.
• In addition to nitrogen and oxygen, carbon dioxide, and water vapour (nearly all of the water vapour contained in the atmosphere is concentrated in the troposphere) and numerous particles of various origin
• The thickness of the Troposphere is maximum at the equator, deeper in the tropics, up to 20 km, and shallower near the polar regions, at 7 km in summer, and indistinct in winter.
• In India, it is taken to be around 16 Kilometers.
• The thickness of the troposphere and consequently the atmosphere  is maximum at the equator
• The boundary between the troposphere and stratosphere, called the tropopause, is a temperature inversion. 

​Stratosphere

• The stratosphere is the second major layer of Earth’s atmosphere, just above the troposphere, and below the mesosphere.
• It is called stratosphere because it is stratified in temperature, with warmer layers higher up and cooler layers farther dow
• The stratosphere is free from the violent weather changes in the Troposphere. So, it is preferred by commercial airliners. 

 Mesosphere

• it extends above the stratosphere up to a height of about 80 km.
• It is the coldest layer of the atmosphere.
• The mesosphere is directly above the stratosphere.
• The stratosphere and mesosphere are collectively termed as " Middle atmosphere "
• Within the mesosphere, temperature decreases with increasing height.

Thermosphere

• The thermosphere starts just above the mesosphere and extends to 600 kilometers (372 miles). {Between 40 km-400km}
• Aurora and satellites occur in this layer.

The correct answer is Mesosphere.

• Mesosphere:
  • This is the highest layer of the atmosphere in which the gases are all mixed up rather than being layered by their mass.
  • Meteors burn up in this layer after entering Earth's atmosphere and before reaching Earth's surface.
  • The meteors make it through the exosphere and thermosphere without much trouble because those layers don’t have much air. 
  • But when they hit the mesosphere, there are enough gases to cause friction and create heat.

Additional Information

• Troposphere:
  • The troposphere is the innermost layer of Earth’s atmosphere.
  • This layer gets its name from the weather that is constantly changing and mixing up the gases in this part of our atmosphere.
  • This layer has the air we breathe and the clouds in the sky. 
• Stratosphere:
  • The stratosphere is located above the troposphere and below the mesosphere.
  • There are no storms or turbulence here to mix up the air, so cold, heavy air is at the bottom and warm, light air is at the top. 
  • The ozone layer found in this stratosphere helps protect us from ultraviolet radiation (UV) from the sun by blocking UV radiations from reaching the Earth’s surface.
  • The ozone layer absorbs most of the UV radiation sends to us by the sun.
• Thermosphere:
  • The thermosphere is located above the mesosphere and below the exosphere.
  • The thermosphere is home to the International Space Station as it orbits Earth.

The correct answer is Poles.

Important Points

• The ozone layer is a natural layer of gas in the upper atmosphere that protects humans and other living things from harmful ultraviolet (UV) radiation from the sun.
• The ozone layer is typically thicker over the poles than over the equator.
• The ozone layer exists in the stratosphere, a layer 10 to 50 km above the Earth’s surface.
• The reasons for ozone depletion are a wide range of industrial and consumer applications, mainly refrigerators, air conditioners (hydrochlorofluorocarbons (HCFCs), chlorofluorocarbons (CFCs)), and fire extinguishers.
• Ozone depletion is greatest at the South Pole (Antarctica).

Key Points

• This severe depletion creates the so-called “ozone hole”.
• The Negative Effects of the ozone hole are certain types of skin cancers, eye cataracts, and immune deficiency disorders.
  • UV rays also affect plant growth, reducing agricultural productivity.
• The international community established the Montreal Protocol on ozone-depleting substances in 1987, to address the destruction of the ozone layer.

The correct answer is Within the mesosphere, temperature increases with increasing height.

Key Points

 Mesosphere - 

• It extends above the stratosphere up to a height of about 80 km.
• It is the coldest layer of the atmosphere.
• The mesosphere is directly above the stratosphere.
• The stratosphere and mesosphere are collectively termed as " Middle atmosphere 
• Within the mesosphere, temperature decreases with increasing height, due to decreasing solar heating and increasing cooling by CO₂ radiative emission.

Additional Information

• There are a total of five atmospheric layers.
• These are - 

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
   • Ionosphere: the lowest part of the Thermosphere contains the ionosphere
5. Exosphere

The correct answer is Troposphere.

• Almost all the clouds are found in the Troposphere.

Key Points

• Troposphere
  • The troposphere is the lowest portion of Earth’s atmosphere and contains approximately 80% of the atmosphere’s mass and 99% of its water vapour and aerosols.
  • The average depth of the troposphere is approximately 17 km in the middle latitudes.
  • The characteristic features of the Troposphere are its great density.
  • In addition to nitrogen and oxygen, carbon dioxide, and water vapour (nearly all of the water vapour contained in the atmosphere is concentrated in the troposphere) and numerous particles of various origin
  • It thickness of the Troposphere is maximum at the equator, deeper in the tropics, up to 20 km, and shallower near the polar regions, at 7 km in summer, and indistinct in winter.
  • In India, it is taken to be around 16 Kilometers.
  • The thickness of the troposphere and consequently the atmosphere is maximum at the equator.
  • Almost all the clouds are found in the troposphere.

Additional Information

• Stratosphere
  • It is the second layer of the atmosphere found above the troposphere.
  • It extends up to 50 km in height.
  • This layer is very dry as it contains little water vapour.
  • This layer provides some advantages for flight because it is above stormy weather and has steady, strong, horizontal winds.
  • The ozone layer is found in this layer.
  • The ozone layer absorbs UV rays and safeguards the earth from harmful radiation.
  • Stratopause separates Stratosphere and Mesosphere. 
• Mesosphere
  • It is the coldest of the atmospheric layers.
  • The mesosphere starts at 50 km above the surface of Earth and goes up to 85 km.
  • The temperature drops with altitude in this layer.
  • By 80 km it reaches -100 degrees Celsius.
  • Meteors burn up in this layer.
  • Mesopause separates Mesosphere and Thermosphere. 
• Thermosphere
  • This layer is found above Mesopause from 80 to 400 km.
  • Radio waves that are transmitted from the earth are reflected by this layer.
  • The temperature increases with height.
  • Satellites occur in this layer.
• Exosphere
  • It is the outermost layer of the atmosphere.
  • The zone where molecules and atoms escape into space is mentioned as the exosphere.
  • It extends from the top of the thermosphere up to 10,000 km.

• 

The correct answer is Troposphere.

Key Points

• Troposphere
  • The troposphere is the lowest layer of the Earth's atmosphere.
  • The air is very well mixed and the temperature decreases with altitude.
  • The air in the troposphere is heated from the ground up.
  • The surface of the Earth absorbs energy and heats up faster than the air does.

Additional Information

• The different layers of the atmosphere are listed below:
  • Exosphere
    • This is the upper limit of our atmosphere.
    • It extends from the top of the thermosphere up to 10,000 km (6,200 mi).
  • Thermosphere
    • The layer present right above the mesosphere extending to a height of 450 km is the thermosphere.
    • Aurora and satellites occur in this layer.
    • This layer is composed of electrically charged ions that are responsible for reflecting the radio waves back to the Earth's surface.
      • Due to the presence of these ions, the thermosphere is also known as the ionosphere.
  • Mesosphere
    • The mesosphere starts just above the stratosphere and extends to 85 km (53 miles) high.
    • Meteors burn up in this layer.
  • Stratosphere
    • The stratosphere starts just above the troposphere and extends to 50 km (31 miles) high.
    • The ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer.

The correct answer is lonosphere.

Key Points

• The ionosphere is the upper layer of the Earth’s atmosphere.
• The atmosphere is partly ionized by solar UV-light, and such ionization can persist at high altitudes.
• The ionosphere starts at about 80 km altitude and reaches up to more than 1000 km.
• This area of the atmosphere consists of several conductive layers that reflect radio waves, a characteristic that is of interest to scientists and engineers, especially in the telecommunications industry.

Additional Information

• Earth's atmosphere has a series of layers, each with its own specific traits. Moving upward from ground level, these layers have named the troposphere, stratosphere, mesosphere, thermosphere, Ionosphere, and exosphere.
• Troposphere
  • The troposphere is the lowest layer of our atmosphere.
  • Starting at ground level, it extends upward to about 10 km above sea level.
  • Humans live in the troposphere, and nearly all weather occurs in this lowest layer.
  • Most clouds appear here, mainly because 99% of the water vapor in the atmosphere is found in the troposphere.
• Stratosphere
  • The next layer up is called the stratosphere.
  • The stratosphere extends from the top of the troposphere to about 50 km above the ground.
  • The ozone layer is found within the stratosphere.
  • Commercial passenger jets fly in the lower stratosphere, partly because this less-turbulent layer provides a smoother ride.
• Mesosphere
  • Above the stratosphere is the mesosphere.
  • It extends upward to a height of about 85 km above our planet.
  • Most meteors burn up in the mesosphere.
  • The coldest temperatures in Earth's atmosphere, about -90° C (-130° F), are found near the top of this layer.
• Thermosphere
  • The layer of very rare air above the mesosphere is called the thermosphere.
  • The thermosphere starts just above the mesosphere and extends to 600 kilometres high.
  • High-energy X-rays and UV radiation from the Sun are absorbed in the thermosphere.
  • Raising its temperature to hundreds or at times thousands of degrees.
  • Many satellites actually orbit Earth within the thermosphere.
  • The aurora, the Northern Lights, and Southern Lights occur in the thermosphere.
• Exosphere
  • This is the upper limit of our atmosphere. It extends from the top of the thermosphere up to 10,000 km.

The correct answer is Thermosphere.

Key Points

• The thermosphere layer of the Atmosphere helps in Radio Transmission.
• It is located above the mesosphere and below the exosphere.
• In the thermosphere, the temperature rises rapidly with increasing height.
• The ionosphere is a part of this layer. 
• This layer helps in radio transmission and in fact, radio waves transmitted from the earth are reflected back to the earth by this layer.
• This layer is home to the International Space Station as it orbits Earth. 

Additional Information The troposphere

• It is the lowermost layer of the atmosphere.
• Its average height is 13 km and extends roughly to a height of 8 km near the poles and about 18 km at the equator.
• The thickness of the troposphere is greatest at the equator because heat is transported to great heights by strong convectional currents.
• This layer contains dust particles and water vapor.
• All changes in climate and weather take place in this layer.
• The temperature in this layer decreases at the rate of 1°C for every 165m of height.
• This is the most important layer for all biological activity.

The stratosphere

• It is found above the tropopause and extends up to a height of 50 km.
• One important feature of the stratosphere is that it contains the ozone layer.
• This layer absorbs ultraviolet radiation and shields life on the earth from an intense, harmful form of energy.

The mesosphere

• It lies above the stratosphere, which extends up to a height of 80 km.
• In this layer, once again, the temperature starts decreasing with the increase in altitude and reaches up to minus 100°C at a height of 80 km.
• The upper limit of the mesosphere is known as mesopause.

The exosphere

• It is the uppermost layer of the atmosphere.
• This is the highest layer but very little is known about it.
• Whatever contents are there, these are extremely rarefied in this layer, and it gradually merges with outer space.