Maharashtra Board Class 6 Science Chapter 1 Natural Resources – Air Water and Land
Q: What are the three spheres of the earth and what do they consist of?
A: The three spheres of the earth are the atmosphere, hydrosphere, and lithosphere. The atmosphere is the layer of air that surrounds the earth, the hydrosphere consists of all the water on the earth’s surface, and the lithosphere is the solid portion of the earth’s surface, including the continents and ocean floors.
Q: What is the biosphere?
A: The biosphere is the living component of the earth, consisting of all the living things that occupy the three spheres of the earth, as well as the parts of those spheres that support life.
Q: Which sphere occupies a larger part of the earth’s surface, the hydrosphere or the lithosphere?
A: The hydrosphere occupies a much larger part of the earth’s surface than the lithosphere.
Q: What is the proportion of land and water on the earth’s surface?
A: The proportion of land and water on the earth’s surface is shown in Figure 1.2. According to the passage, the hydrosphere occupies a much larger part of the earth’s surface than the lithosphere.
Q: How do we use the natural components of the earth as resources?
A: We use the natural components of the earth, including air, water, and land, in their solid, liquid, and gaseous forms, as resources to fulfil our requirements.
Q: What are some of the gases that make up the air in the earth’s atmosphere?
A: The air in the earth’s atmosphere contains nitrogen, oxygen, carbon dioxide, six inert gases, nitrogen dioxide, sulphur dioxide, and water vapour. Additionally, it contains dust particles.
Q: What is the troposphere and how does it differ from the stratosphere in terms of gas composition?
A: The troposphere is the lowest layer of the earth’s atmosphere, extending from the surface up to about 10-15 kilometres in altitude. It contains about 80% of the total mass of gases in the air. In contrast, the proportion of gases in the stratosphere is about 19%.
Q: How does the proportion of gases in the air change as altitude increases?
A: The amount of gases in the air is greatest near the surface and decreases as altitude increases. This means that air becomes rarer at higher altitudes.
Q: What are some of the components of air besides gases?
A: In addition to gases, air also contains water vapour and dust particles.
Q: In which layers of the earth’s atmosphere does the proportion of gas mass decrease?
A: In the mesosphere and ionosphere layers of the earth’s atmosphere, the proportion of gas mass goes on decreasing.
Q: What is the role of nitrogen in living things and in packaging foodstuffs?
A: Nitrogen helps living things to build the necessary proteins, and it is useful in the production of ammonia and in airtight packaging of foodstuffs.
Q: Why is oxygen important?
A: Oxygen is necessary for respiration in living things and for combustion.
Q: How do plants use carbon dioxide, and in what other application is it used?
A: Plants use carbon dioxide for producing their food, and it is also used in fire extinguishers.
Q: What are some applications of argon, helium, neon, krypton, and xenon?
A: Argon is used in electric bulbs, helium is used for obtaining low temperature and also for generating lift in airships, neon is used in decorative lights and for street lighting, krypton is used in fluorescent tubes, and xenon is used in flash photography.
Q: What happens when smoke mixes with the atmosphere?
A: When smoke mixes with the atmosphere, it disturbs the balance between the constituents of air. This is called air pollution.
Q: How are harmful gases given out into the air?
A: Harmful gases are given out through combustion of fuels in vehicles and in big industries and also through incomplete combustion of fuels like wood and coal.
Q: What are some sources of air pollution?
A: Some sources of air pollution include emissions from vehicles and industries, burning of fossil fuels, and forest fires.
What is the importance of the ozone layer for living things?
The ozone layer is important for living things because it absorbs harmful ultraviolet rays coming from the sun, protecting life on earth.
What is ozone and where is it found?
Ozone is a gas made up of three oxygen atoms (O3), and it is found in the lower part of the stratosphere.
How is the ozone layer destroyed?
The ozone layer can be destroyed if chemical gases like carbon tetrachloride or chlorofluorocarbons used in air conditioners and refrigerators mix with the air.
Why is September 16th celebrated as Ozone Protection Day?
September 16th is celebrated as Ozone Protection Day all over the world to raise awareness about the importance of the ozone layer and the need to protect it.
What are the natural sources of water?
The natural sources of water include streams, rivers, ponds, springs, and lakes.
What are some man-made sources of water?
Man-made sources of water include wells, bore wells, bunds, and dams of various sizes on rivers.
Why is water scarcity a serious problem?
Water scarcity is a serious problem because of the uncontrolled use of water for an increasing population, industry, and farming. As a result, water is now in short supply.
Why is land important?
Land is an important resource as it is used by terrestrial animals for shelter, for farming, building houses and roads, and for obtaining minerals, crude oil, and natural gas.
What is the topmost layer of mature soil called?
The topmost layer of mature soil is called ‘humus’.
What is found below the layer of humus?
Below the layer of humus, there is sand, soil, small stones, worms, and insects.
How is soil on the land formed?
The soil on the land is formed by a natural process where the bedrock breaks down into pieces due to the heat, cold, wind, and rain. Stones, sand, and soil are formed from these pieces. Microbes, worms, and insects are found among them, and rodents like mice and rats are also found here.
How long does it take for a 2.5 cm thick layer of mature soil to form?
It takes about a thousand years for a 2.5 cm thick layer of mature soil to form through a slow and continuous process.
Question: Why is it necessary to conserve soil and prevent erosion of land?
Answer: It is necessary to conserve soil and prevent erosion of land because soil can get destroyed in a short period of time due to natural disasters such as floods and storms, as well as human activities such as mining. Soil erosion can lead to loss of fertile topsoil, reduced agricultural productivity, and environmental degradation. To prevent erosion of land and conserve soil, it is important to increase the green cover of the land by growing grass, trees and bushes which can help reduce erosion.
Question: What is humus and what is its role in soil?
Answer: Humus is the layer formed on soil due to the decomposition of dead plants and animals. It supplies nutrients to the soil, aerates the soil and holds water in the soil. The proportion of humus in the upper layer of good fertile soil is about 33% to 50%.
