Class 6 Geography Chapter 5 Practice Question Answers - Major Domains of the Earth

Q1: Density of the air decreases with the increase in_________.
Ans: Height.

Q2: What is Eurasia?
Ans: The combined landmass of Europe and Asia.

Q3: Name the most important river of China?
Ans: River Yangtze.

Q4: Why do climbers often experience breathing problems?
Ans: The climbers experience problems in breathing due to decrease in the density of air. They have to carry with them oxygen cylinders to be able to breathe at higher altitude as the density of air keeps on decreasing with increase in altitude.

Q5: The three domains of the earth interact with each other and affect each other in some way. Discuss.
Ans: The three domains of the earth interact with each other and affect each other. For example, the industrial effluents are thrown on the land from where they gradually flow into rivers, lakes and other water bodies. Hence, polluting both land and water. The polluted release of smoke and other gases further pollute the atmosphere. So, all the major domains are affected by one common source.

Q6: Write in brief about the lithosphere.
Ans: The atmosphere is composed mainly of nitrogen and oxygen, which make up about 99 per cent of clean, dry air. Nitrogen 78 per cent, oxygen 21 per cent and other gases like carbon dioxide, argon and others comprise 1 percent by volume. Oxygen is the breath of life while nitrogen helps in the growth of living organisms. Carbon dioxide, though present in minute amount, is important as it absorbs heat radiated by the earth. It is also essential for the growth of plants.

Q7: Write a short note on Antarctica.
Ans: Antarctica lies completely in the southern hemisphere. At the centre of the continent is the South Pole. It is permanently covered with thick ice sheets. There are no permanent human settlements here. Many countries have set up there research station here. Maitri and Dakshin Gangotri are Indian research centres.

Q8: Describe water cycle.
Ans: The continuous changes of the state and movement of water throughout the Earth system, i.e., the atmosphere, biosphere, lithosphere and hydrosphere is known as the water cycle. The water cycle is driven by energy from the Sun rays, which cause liquid water from Earth's surface to change into gas in a process called evaporation. As gaseous vapour rises and circulates in the atmosphere, it cools and changes back into a liquid, a process known as condensation. When water vapour condenses, tiny droplets form clouds, which return the water to Earth as precipitation.

Q9: How does the atmosphere act as a blanket?
Ans: Atmosphere acts as a blanket of the earth because it maintains a fairly even temperature both during day and night. Atmosphere also shields the earth from the strong ultraviolet rays of the sun due to the presence of ozone gas. It also protects earth from meteors.

Q10: What do you mean by Strait? Name the Strait between India and Sri Lanka.
Ans: A strait is a narrow passage of water connecting two large water bodies like seas and oceans. The strait between India and Sri Lanka is Palk Strait.

Q11: How do old and young mountains differ?
Ans: Old mountains have rounded features and are low in height such as Aravallis. It is because they are very old and have been eroded by the forces of nature like wind, water, etc. over a long period. Young mountains have conical features and are greater in height.The best example of young folded mountains is Himalaya.

Q12: Mention the layers of the atmosphere. Name the closest layer to the earth's surface?
Ans: The different layers of the atmosphere are:

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Exosphere

Troposphere is the closest layer to the earth's surface.

Q13: Why is the Northern Hemisphere called the land Hemisphere?
Ans: The Northern Hemisphere is called the land hemisphere because the greater part of continental landmass lies in the northern hemisphere wh

Q14: What is acid rain?
Ans: Rainwater is naturally acidic due to carbon dioxide, which partially reacts with water to give carbonic acid. When we talk about acid rain, we mean the enhanced effect which is caused by other gases released when fossil fuels are burnt. Two main gases are: Sulphur dioxide and Nitrogen oxide. The dilute acid falls to ground as acid rain.

Q15: Inspite of being called the Blue Planet, the earth experiences shortage of water. Why?
Ans: The earth experiences water shortage because 97% of the earth’s water is found in the oceans and is too salty for human use. Of the remaining 3%, large proportion is in the form of ice sheets, glaciers and under the ground. A very small percentage is available as fresh water.

Q16: What is ozone depletion?
Ans: Ozone depletion occurs when the natural balance between the production and destruction of stratospheric ozone is tipped. Although natural phenomena can cause temporary ozone losses, man-made synthetic compounds such as CFCs are now accepted as the main cause of this depletion. Ozone depletion, in fact, is occurring all over the world due to man-made pollution, at 19 to 30 km above the Earth's surface. However, in certain parts of the world, ozone depletion is particularly severe.

Q17: What is a plateau? Name the two important plateaus of the world.
Ans: A plateau is a large area of fairly level land rising much above the surrounding areas. A plateau may have steep slopes on one or more sides. The height of the plateau may range from 400 meters to several thousand meters above sea level. These are almost flat. Deccan Plateau of India and the plateau of Africa are two important examples.

Q18: Why is the Biosphere important for living organisms?
Ans: Biosphere is the sphere of living organisms, where lithosphere, hydrosphere and atmosphere meet and interact. Every living species on the earth is a part of the biosphere. The organisms in the biosphere are broadly divided into plants, animals, humans beings and microbes. These elements are interdependent on one another and there is continuous interaction between them. They provide food and raw materials. The survival of the living organisms on the earth depends upon the biosphere. Thus, this sphere is so important.

Q19: What are the major effects of water pollution?
Ans: The major effects of water pollution are:

• The food chain is damaged. When toxins are in water, the toxins travel from the water to the animals and to humans when the animal's meat is eaten.
• Diseases can spread via polluted water. Infectious diseases such as typhoid and cholera can be extended from drinking contaminated water.
• Acid rain contains sulfate particles, which can harm fish or plant life in lakes and rivers.
• Pollutants in the water will alter the overall chemistry of the water, causing changes in acidity, temperature and conductivity. These factors all have an affect on the marine life.
• Marine food sources are contaminated or eliminated by water pollution.
• Altered water temperatures due to human actions can kill the marine life and affect the delicate ecological balance in bodies of water, especially lakes and rivers.

Q20: Which is the second largest continent after Asia? Mention four features of this continent.
Ans: Africa is the second largest continent after Asia. Four features of this continent are:

• The equator passes through the middle of Africa, splitting it into Northern Hemisphere and Southern Hemisphere.
• The Sahara Desert, the world’s largest hot desert, is located in Africa.
• The continent is bound on all sides by oceans and seas.
• The Nile, the world’s longest river flows through this continent.