Science Chapter 14 Class 9 Questions Answers contains all the main and important topics which have a complete and detailed description. Solutions of Chapter 14 Natural Resources of NCERT Science for Class 9 will help the students of class 9 to understand concepts.
Science Chapter 14
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Science Chapter 14 Class 9 Questions Answers
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topics and subtopics of Science Chapter 14 Class 9 Questions Answers before you go through the Solutions of Chapter 14 Natural
Resources of NCERT Science for
Class 9.
Science Chapter 14 Class 9 Questions Answers Overview
1. The Breath of Life: Air
2. Water: A Wonder Liquid
3. Mineral Riches in The Soil
4. Biological Cycles
5. Ozone Layer
Solutions of Chapter 14
Natural Resources of NCERT Science for Class 9 Intext questions
Chapter
14 Natural Resources
Science Chapter 14 Class 9 Questions Answers Intext Questions
Science Chapter 14 Class 9 Questions AnswersPage No. 193
Q.1 How is our atmosphere different from the atmosphere on Venus and Mars?
Ans. Our atmosphere is a mixture of many gases like nitrogen-oxygen, carbon dioxide, and water vapours. The atmosphere of Venus and Mars consists of carbon dioxide only. So there is no life on Venus and Mars.
Q.2 How does the atmosphere act as a blanket?
Ans. Air is a bad conductor of heat and our atmosphere contains air. The atmosphere acts as a protective blanket because it keeps the average temperature of the earth fairly steady during the day and even during the course of the whole year. The atmosphere prevents the sudden increase in temperature during the daylight hours and during the night, it slows down the escape of heat into outer space.
Q.3 What causes wind?
Ans. The energy of the sun is responsible for winds. Winds are caused due to unequal heating of atmospheric air. The air above the land gets heated and starts rising, at this time a low-pressure area is created and air over the sea moves in to this area of low pressure. The movement of air from one region to the other creates winds.
Rotation of the earth, the presence of mountains ranges in the paths of winds also influence it.
Q.4 How are clouds formed?
Ans. When the water bodies are heated with Sun’s radiation during the daytime, a large amount of water evaporates and goes into the environment. The air carrying water vapours also get heated. These hot water vapours rise up with hot air. As the air rises, it expands and cools. On cooling, the water vapours condense into tiny droplets. Dust or other suspended particles present in the air act as the ‘nuclei for these droplets to form around. These droplets of water grow bigger by the condensation of more water droplets. An enormous collection of tiny droplets of water appear as clouds. When the droplets have grown big, they fall down in the form of rain.
Q.5 List any three activities that you think would lead to air pollution.
Ans.(i). Excessive use of fossil fuels like coal and petroleum produces oxides of nitrogen and sulpher which cause air pollution.
(ii). Forest fire, mining process, and excessive use of CFC cause air pollution.
(iii). Incomplete combustion of fuels forms unburnt carbon particles in the air. At the time of cold weather, water condenses and these particles combine with water to form smog which lowers visibility.
Science Chapter 14 Class 9 Questions Answers Page No. 194
Q.1 Why do organisms need water?
Ans. Organisms need water to carry out the following activities:
(i) photosynthesis uses water as a raw material. All cellular processes in all organisms take place in a water medium.
(ii) Water makes up 70% of the bodyweight of all living beings.
(iii) Water acts as a universal solvent and helps in transporting substances from one part of the body to other in a dissolved form.
(iv) It also helps in the digestion of food and absorption of nutrients in the blood.
(v) Water is also required by organisms for many of their activities such as drinking, cooking, washing, irrigation, production of hydel power, etc.
(vi) It helps in maintaining body temperature.
Q.2 What is a major source of fresh water in the city/town/village where you live?
Ans. The major source of fresh water in the city/town/village where we live is underground water and river, lakes, ponds are also the main sources of freshwater.
Q.3 Do you know of any activity which may be polluting this water source?
Ans. Sewage and industrial wastes are the major sources of pollution of river water.
Science Chapter 14 Class 9 Questions AnswersPage No. 196
Q.1 How is soil formed?
Ans. Soil is a mixture of small particles of rocks and humus. Temperature variation due to solar radiation, rainwater, winds, and living organisms influence the formation of soil.
i. The sun heats up rocks during daytime and they expand but at night rocks cool down and contract. This contraction is uneven and this leads to the formation of cracks in the rocks into smaller pieces.
ii. Flow of water through or over the rocks makes the cracks bigger. Falling/flowing water also has to erase the effect on the rocks. On freezing the water expands in rock cervices and breaks the rocks.
iii. Strong winds erode rocks and carry sand from one place to the other.
iv. Living organisms like lichens grow on the surface of rocks. They release substances that cause the rock surface to powder down and form a thin layer of soil.
Q.2 What is soil erosion?
Ans. The removal of the top layer of soil which is rich in humus and nutrients from its original position to another place with the help of certain factors like strong wind and fast running water, is called soil erosion.
Q.3 What are the methods of preventing or reducing soil erosion?
Ans. Soil erosion can be prevented or reduced by:
(i) Intense cropping and use of proper drainage canals.
(ii)Terracing on a slop field retards the flow of water and prevents soil erosion.
(iii) Planting trees and grasses.
(iv) Trees planted in lines around farmland reduce erosion.
(v) By avoiding overgrazing
Science Chapter 14 Class 9 Questions Answers Page No. 201
Q.1 What are the different states in which water is found during the water cycle?
Ans. All three states of water can be seen during the water cycle
(i) Water vapours in the air which ultimately from clouds,
(ii) Rainwater that falls on earth and is available to us in water bodies or as underground water, (iii) Dew, snow, sheet or hail.
Q.2Name two biologically important compounds that contain both oxygen and nitrogen.
Ans. (i) Nucleic acids (DNA and RNA), (ii) Proteins.
Q.3List any three human activities which could lead to an increase in carbon dioxide content air.
Ans. (i) Burning of fossil fuels leads to an increase in carbon dioxide.
(ii) Burning associated with agricultural practices
(iii) Deforestation increase in CO2. Because trees absorb CO2 and convert it into organic compounds by the process of photosynthesis.
Q.4 What is the greenhouse effect?
Ans. The greenhouse is a glass enclosure that is used for growing tropical plants in colder climates even in winters. The glass wall of the greenhouse allows sun rays to enter inside but heat developed inside is not allowed to go out.
This makes greenhouse air warmer than the outside air and the phenomenon is called the greenhouse effect.
An increase in Gases like carbon dioxide in the atmosphere forms a layer around the earth that prevents the heat inside the atmosphere and this leads to an increase the average temperature. This is called Global warming. This is known as the greenhouse effect.
Q.5 What are the two forms of oxygen found in the atmosphere?
Ans. Molecular oxygen (O2) and ozone (O3).
Science Chapter 14 Class 9 Questions Answers End Exercise
Q.1 Why is the atmosphere essential for life?
Ans. The atmosphere is essential for life because:
i. It keeps the average temperature of the earth.
ii. It contains gases which are essential for life. Oxygen present in it is needed by living things to break down glucose molecules and get energy for their activities. Carbon dioxide in the atmosphere is used as raw material in photosynthesis.
iii. It contains all gases that are essential for sustaining life on the earth.
iv. Ozone layer of the atmosphere stop harmful UV radiation from the sun and prevent us from harmful effects.
Q.2 Why is water essential for life?
Ans. Water is essential for life because of the following reasons-
i. photosynthesis uses water as a raw material. All cellular processes in all organisms take place in a water medium.
ii. Water makes up 70% of the bodyweight of all living beings.
iii. Water acts as a universal solvent and helps in transporting substances from one part of the body to other in a dissolved form.
iv. It also helps in the digestion of food and absorption of nutrients in the blood.
v. Water is also required by organisms for many of their activities such as drinking, cooking, washing, irrigation, production of hydel power, etc.
vi. It helps in maintaining body temperature.
Q.3 How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resources?
Ans. Living organisms are dependent on the soil in the following ways-
i. Plants grow on the soil. All living organisms are dependent on plants directly or indirectly for their survival. Thus living organisms are dependent on the soil.
ii. Number of insects, animals that build their home in the soil.
iii. Soil provides essential nutrients to plants.
No, organisms that live in water are not totally independent of soil as a resource because many nutrients present in the soil flow in the water, which is necessary for these organisms. All water bodies have soil beds.
Q.4 You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Ans. We are able to predict the weather in the following ways-
· We have to obtain a detailed picture of present weather conditions in the region for which we wish to predict the weather.
·Various instruments are used to record the reading viz. temperature, air, pressure, humidity, wind (speed and direction), and rainfall.
· We also make visual observations like cloud cover and visibility.
All the information collected is sent to the meteorological department which prepares a weather report. This report is displayed on the maps and transmitted on television and radio and published in the newspapers.
Q.5 We know that many human activities lead to the increasing levels of pollution of air, water bodies, and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?
Ans. Yes, if the human activities are restricted and isolated to specific and limited areas would help in reducing pollution.
i.If all the industries are established far from the residential areas, this can minimize air-borne diseases.
ii. All the sewage of a particular area is collected at one place and after proper treatment, it will be discharged into water bodies. This can prevent aquatic life to a little extent.
iii. Wastewater from the industries must be treated before discharging in water bodies.
iv.We should avoid the use of non-biodegradable substances like plastics, polythene.
Q.6Write a note on how forests influence the air, soil, and water resources?
Ans. Forest is a large area covered thickly with trees and other plants such as shrubs and grasses. Forests are renewable natural resources. Forests influence the air, water, and soil resources in the following ways:
1Forest plants maintain the O2 and CO2 balance in the atmosphere.
2. They prevent the greenhouse effect.
3. Forest maintains the natural environment by influencing such factors as temperature, humidity, and precipitation.
4. Forests maintain the soil environment by affecting its composition, structure, chemical properties, water contents, etc.
5. Roots of forests plants bind the soil and do not allow soil erosion by fast winds or fast-moving water. In this way, they help in maintaining the fertility of the soil. Many bacteria found in root nodules replenish the fertility of the soil.
6. Forest prevents flooding, landslides.
7. Forests regulate the biogeochemical cycles of water, carbon, nitrogen, oxygen, and other elements.
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