NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

These NCERT Solutions for Class 9 Science Chapter 14 Natural Resources Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.

Natural Resources NCERT Solutions for Class 9 Science Chapter 14

Class 9 Science Chapter 14 Natural Resources InText Questions and Answers

Question 1.
How is our atmosphere different from the atmospheres on Venus and Mars?
Answer:
Earth’s atmosphere is different from those of Venus and Mars. This difference lies essentially in their compositions. Earth’s atmosphere is a mixture of nitrogen (79%), oxygen (20%), and a small fraction of carbon dioxide, water vapours and other gases. This makes the existence of life possible on Earth. However, the atmospheres on Venus and Mars mainly consist of carbon dioxide. The amount of carbon dioxide on these planets can range from 95% to 97%.

Question 2.
How does the atmosphere act as a blanket?
Answer:
The atmosphere acts as a blanket by performing the following functions:
(a) It keeps the average temperature of the Earth fairly constant during daytime and even during the course of whole year.
(b) It prevents a sudden increase in the temperature during daytime.
(c) It slows down the escape of heat from the surface of the Earth into outer space during nighttime.

Question 3.
What causes winds?
Answer:
An uneven heating of the Earth’s surface causes winds. On being heated, air becomes lighter and rises up. As a result, a region of low pressure is created. Then, air from a high pressure region moves to a low pressure region, causing wind.

Question 4.
How are clouds formed?
Answer:
During daytime, on being heated, a large amount of water evaporates from various water bodies and goes into the air. A part of this water vapour also reaches the atmosphere through biological activities such as transpiration and respiration. This causes the air in the atmosphere to heat up. When this heated air rises, it expands and cools, which results in the condensation of water vapour forming water droplets. The presence of dust and other suspended particles in air also facilitates the process of condensation. The formation of water droplets leads to the formation of clouds.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 5.
List any three human activities that you think would lead to air pollution.
Answer:
The following three human activities would lead to air pollution:

  1. Burning of fossil fuels such as coal and petroleum
  2. Industrialization
  3. Deforestation

Question 6.
Why do organisms need water?
Answer:
Organisms need water for the following reasons:

  • All cellular processes need water as a medium. Usually, the reactions that take place in our body or within the cells occur between substances that are dissolved in water.
  • Since most of the substances are transported in a dissolved form, water is necessary.

Question 7.
What is the major source of fresh water in the city/town/village where you live?
Answer:
River is a major source of freshwater.

Question 8.
Do you know of any activity which may be polluting this water source?
Answer:
The discharge of wastewater from homes, industries, hospitals, etc. into the river pollutes this freshwater source.

Question 9.
How is soil formed?
Answer:
Soil is formed by breaking down of rocks at or near the surface of the Earth through various physical, chemical, and biological processes by various factor such as the sun, water, wind, and living organisms.
(i) Sim:
During day time, the rocks are heated. This
causes the rocks to expand. During nighttime, these rocks cool down and contract. Since all parts of the rock do not undergo expansion and contraction at the same rate, this causes the formation of cracks in these rocks. These cracks lead to the breaking up of huge rocks into smaller pieces.

(ii) Water:
Water catalyses the process of formation of soil in two ways.
(a) Water goes into the cracks and crevices formed in the rocks. When this water freezes, its volume increases. As a result, the size of the cracks also increases. This helps in the weathering of rocks.
(b) Running water wears away hard rocks over long periods of time. Water moving in fast speed carries big and small particles of rock downstream. These rocks rub against each other, resulting in breaking down of rocks. These smaller particles are carried away by running water and deposited down its path.

(iii) Wind:
Strong winds carry away rocks, which causes rubbing of rocks. This results in the breaking down of rocks into smaller and smaller particles.

(iv) Living organisms:
Some living organisms like lichens help in the formation of soil. Lichens also grow on rocks. During their growth, lichens release certain substances, which cause the rock surface to powder down forming a thin layer of soil. On this thin layer of soil, some small plants like moss also grow. They further cause the breaking down of the rock particles.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 10.
What is soil erosion?
Answer:
The blowing away or washing away of land surface by wind or water is known as soil erosion.

Question 11.
What are the methods of preventing or reducing soil erosion?
Answer:
The methods of preventing or reducing soil erosion are:

  • Prevention of deforestation
  • Plantation of trees

Question 12.
What are the different states in which water is found during the water cycle?
Answer:
During the water cycle, water is found in solid state (snow, ice, etc.), liquid state (ground water, river water, etc.), and gaseous state (water vapours).

Question 13.
Name two biologically important compounds that contain both oxygen and nitrogen.
Answer:
Two biologically important compounds that contain both oxygen and nitrogen are:

  1. Amino acids
  2. Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

Question 14.
List any three human activities which would lead to an increase in the carbon dioxide content of air.
Answer:

  1. Burning of fuels in various processes like heating, cooking, transportation, and industry.
  2. Human induced forest fires
  3. The process of deforestation includes the cutting down of trees. This decreases the uptake of carbon dioxide for photosynthesis. Eventually, the content of carbon dioxide increases.

Question 15.
What is the greenhouse effect?
Answer:
Some gases like carbon dioxide, methane, nitrous oxide prevent the escape of heat from the Earth’s surface by trapping it. This increases the average temperature of the Earth. This is called the greenhouse effect. An increase in the content of such gases would lead to a situation of global warming.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 16.
What are the two forms of oxygen found in the atmosphere?
Answer:
The two forms of oxygen found in the atmosphere are:

  1. Diatomic molecular form with chemical formula O2.
  2. Triatomic molecular form with chemical formula O3 known as ozone.

Class 9 Science Chapter 14 Natural Resources Textbook Questions and Answers

Question 1.
Why is the atmosphere essential for life?
Answer:
The atmosphere is essential for life because it maintains an appropriate climate for the sustenance of life by carrying out the following activities:

  • Atmosphere keeps the average temperature of the Earth fairly constant during daytime.
  • It prevents a sudden increase in temperature during daytime.
  • It also slows down the escape of heat from the surface of the Earth into outer space during nighttime.

Question 2.
Why is water essential for life?
Answer:
Water is essential for life because of the following reasons:

  • Most biological reactions occur when substances are dissolved in water. Thus, all cellular processes need water as a medium to take place.
  • Transportation of biological substances needs water as a medium.

Question 3.
How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?
Answer:
Almost all living organisms are dependent on soil. Some depend directly, while some depend indirectly.

Plants need soil for getting support as well as nutrients to prepare their food. On the other hand, organisms depend on plants for food and other substances that are essential for life. Herbivores depend directly upon plants, and carnivores depend upon animals, which in turn depend upon plants for food. This makes them depend on soil indirectly.

Organisms that live in water are not totally independent of soil as a resource. These organisms depend on aquatic plants for food and other substances. These aquatic plants in turn require minerals for their sustenance. These minerals are carried to water bodies from soil by rivers, rainwater, etc. Without the supply of minerals from the soil to the water bodies, it is impossible to imagine aquatic life.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 4.
You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Answer:
The meteorological department of the government collects data on the elements of weather such as maximum and minimum temperatures, maximum and minimum humidity, rainfall, wind speed, etc. They are able to study these elements using various instruments. The maximum and minimum temperature of a day is measured by a thermometer known as the maximum-minimum thermometer. Rainfall is measured by an instrument known as the rain gauge. Wind speed is measured by anemometers. There are various instruments used to measure humidity.

Question 5.
We know that many human activities lead to increasing levels of pollution of the air, water-bodies and soiL Do you think that isolating these activities to specific and limited areas would help in reducing pollution?
Answer:
Yes. Isolating human activities to specific areas would help in reducing levels of pollution. For example, setting up of industries in isolated regions will control pollution to some extent. The pollution caused by these industries will not contaminate water resources, agriculture land, fertile land, etc.

Question 6.
Write a note on how forests influence the quality of our air, soil and water resources.
Answer:
Forests influence the quality of our air, soil, and water resources in various ways. Some of them are:

  • Forests balance the percentages of carbon dioxide and oxygen in the atmosphere. The increasing amount of carbon dioxide caused by human activities is balanced by a larger intake of carbon dioxide by plants during the process of photosynthesis. Simultaneously, a large amount of oxygen is released.
  • Forests prevent soil erosion. Roots of plants bind the soil tightly in a way that the surface of the soil cannot be eroded away by wind, water, etc.
  • Forests help in the replenishment of water resources. During the process of transpiration, a huge amount of water vapour goes into the air and condenses to form clouds. (These clouds cause rainfall that recharge water bodies.

Class 9 Science Chapter 14 Natural Resources Additional Important Questions and Answers

Choose the correct option:

Question 1.
The atmosphere of the earth is heated by radiations which are mainly
(a) radiated by the sun
(b) re-radiated by land
(c) re-radiated by water
(d) re-radiated by land and water
Answer:
(d) re-radiated by land and water

Question 2.
If there were no atmosphere around the earth, the temperature of the earth will
(a) increase
(b) go on decreasing
(c) increase during day and decrease during night
(d) be unaffected
Answer:
(c) increase during day and decrease during night

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 3.
What would happen, if all the oxygen present in the environment is converted to ozone?
(a) We will be protected more
(b) It will become poisonous and kill living forms
(c) Ozone is not stable, hence it will be toxic
(d) It will help harmful sun radiations to reach earth and damage many life forms.
Answer:
(b) It will become poisonous and kill living forms

Question 4.
One of the following factors does not lead to soil formation in nature
(a) the sun
(b) water
(c) wind
(d) polythene bags
Answer:
(d) polythene bags

Question 5.
The two forms of oxygen found in the atmosphere are
(a) water and ozone
(b) water and oxygen
(c) ozone and oxygen
(d) water and carbon-dioxide
Answer:
(c) ozone and oxygen

Question 6.
The process of nitrogen-fixation by bac¬teria does not take place in the presence of
(a) molecular form of hydrogen
(b) elemental form of oxygen
(c) water
(d) elemental form of nitrogen
Answer:
(b) elemental form of oxygen

Question 7.
Rainfall patterns depend on
(a) the underground water table
(b) the number of water bodies man area
(c) the density pattern of human population in an area
(d) the prevailing season in an area
Answer:
(b) the number of water bodies man area

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 8.
Among the given options, which one is not correct for the use of large amount of fertilisers and pesticides?
(a) They are eco-friendly
(b) They turn the fields barren after some time
(c) They adversely affect the useful component from the soil
(d) They destroy the soil fertility
Answer:
(a) They are eco-friendly

Question 9.
The nitrogen molecules present in air can be converted into nitrates and nitrites by
(a) a biological process of nitrogen fixing bacteria present in Soil
(b) a biological process of carbon fixing factor present in soil
(c) any of the industries manufacturing nitrogenous compounds
(d) the plants used as cereal crops in field
Answer:
(a) a biological process of nitrogen fixing bacteria present in Soil

Question 10.
One of the following processes is not a step involved in the water-cycle operating in nature
(a) evaporation
(b) transpiration
(c) precipitation
(d) photosynthesis
Answer:
(d) photosynthesis

Question 11.
The term “water-pollution” can be defined in several ways. Which of the following statements does not give the correct definition?
(a) The addition of undesirable substances to water-bodies
(b) The removal of desirable substances from water-bodies
(c) A change in pressure of the water bodies
(d) A change in temperature of the water bodies
Answer:
(c) A change in pressure of the water bodies

Question 12.
Which of the following is not a greenhouse gas?
(a) Methane
(b) Carbon dioxide
(c) Carbon monoxide
(d) Ammonia
Answer:
(d) Ammonia

Question 13.
Which step is not involved in the carbon-cyicle?
(a) Photosynthesis
(b) Transpiration
(c) Respiration
(d) Burning of fossil fuels
Answer:
(b) Transpiration

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 14.
‘Ozone-hole’ means
(a) a large sized hole in the ozone layer
(b) thinning of the ozone layer
(c) small holes scattered in the ozone layer
(d) thickening of ozone in the ozone layer
Answer:
(b) thinning of the ozone layer

Question 15.
Ozone-layer is getting depleted because of
(a) excessive use of automobiles
(b) excessive formation of industrial units
(c) excessive use of man-made compounds containing both fluorine and chlorine
(d) excessive deforestation.
Answer:
(c) excessive use of man-made compounds containing both fluorine and chlorine

Question 16.
Which of the following is a recently originated problem of environment?
(a) Ozone layer depletion
(b) Greenhouse effect
(c) Global warming
(d) All of the above

Very Short Answer Questions

Question 1.
Define the term natural resource.
Answer:
Any useful material obtained from the nature is called a natural resource.

Question 2.
What are two types of natural resources?
Answer:
The two types of natural resources are renewable resources and non-renewable resources.

Question 3.
Which zone of atmosphere is the closet to the earth?
Answer:
Troposphere

Question 4.
Name the three important constituents of the air.
Answer:
The three important constituents of soil are nitrogen, oxygen and carbon dioxide.

Question 5.
Where on earth the British researchers have found the ozone hole in 1985?
Answer:
Over South Antarctica.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 6.
Montreal protocol in 1986 had banned on the emission of a pollutant to protect the ozone layer. Name the pollutant.
Answer:
Montreal protocol had banned the emission of CFCs (Chlorofluro carbon)

Question 7.
Name some of the greenhouse gases.
Answer:
Carbon dioxide, methane, sulphur dioxide and CFCs.

Question 8.
Which two types of components are found in biosphere?
Answer:
Biotic (living) components and abiotic (Non-living) components.

Question 9.
List the factors which contribute to the weathering of rocks in soil formation.
Answer:
The factors are temperature, air, water and living organisms like lichens.

Question 10.
Which factor is responsible for deciding the type of soil?
Answer:
The average particle size decides the type of soil.

Question 11.
Which type of soil causes early waterlogging conditions?
Answer:
Clayey soil

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 12.
Why is there a need to conserve the natural resources?
Answer:
The conservation of natural resources is essential for the sustainable development.

Question 13.
What is biosphere?
Answer:
The life supporting zone, of the earth where the lithosphere, hydrosphere and atmosphere interact is called biosphere.

Question 14.
What do you understand by top soil?
Answer:
The top soil is the uppermost layer of soil that contains humus and living organisms in addition to soil particles. It also holds the plants.

Question 15.
Name the three forms of nitrogen fixation.
Answer:
The three forms of nitrogen fixation are atmospheric fixation, biological fixation and industrial fixation.

Short Answer Questions

Question 1.
What is atmosphere? State its importance to life on the earth.
Answer:
A thick blanket of air present around the earth is called atmosphere. It is a bad conductor of heat as during day time, the atmospheric gases prevents excessive rise in surface temperature of the earth for the survival of life and at night time the same gases prevent the escape of heat from earth surface to keep it warm.

The air present in atmosphere also contains life supporting gases such as oxygen and carbon dioxide.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 2.
Mention the different constituents of the soil.
Answer:
The different constituents of soil are

  • Powdered rock particles formed after the weathering of rocks.
  • Micro-organisms included in the decomposition of organic matter.
  • Water droplets
  • Organisms like earthworm for whom the top soil acts as their habitat.

Question 3.
Why is soil important for plants?
Answer:
Soil is important to plants because it is a source of

  • water required by the plants.
  • mineral nutrients required by the plants
  • support required by plants to stand erect even in windy or stormy conditions.

Question 4.
What is soil pollution?
Answer:
The removal of useful components of soil and the addition of other substances which interfere with the soil fertility and harm the diversity of microorganisms present in soil is called soil pollution. The application of chemical fertilizers, pesticides and addition of domestic and industrial waste to soil, along with increased degree of soil erosion are the major causes of soil pollution.

Question 5.
Differentiate in water table and water depth.
Answer:
The minimum depth fo soil where all pore spaces in soil are filled with water make up the water table. Thus, the upper level zone of saturation is called water table.The depth of water level is expressed with reference to mean sea level.

The vertical distance from place on the surface of the earth to the water table is called the water level.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 6.
Differentiate in the two types of components found in the biosphere.
Answer:
The types of the components found in the biosphere are biotic and abiotic components. The biotic components include all living organisms from microorganisms to higher plants and animals. The abiotic components include all non-living components such as air, water and soil.

Question 7.
Why do we need to conserve the natural resources?
Answer:
The conservation of natural resources means their wise and judicious use. It is essential to conserve the different natural resources to ensure

  • The availability of natural resources for a longer time.
  • The maintenance of the quality of the natural resources.
  • To achieve the sustainable development.

Question 8.
List two ways in which carbon dioxide is fixed in nature.
Answer:
The carbon dioxide is fixed in nature by

  1. Green plants who produce sugar by the reduction of carbon dioxide in photosynthesis.
  2. Aquatic mostly marine animals molluscs who use carbonates present in seawater to make their protective shell

Question 9.
Mention some of the pollutants of air.
Answer:
Any undesirable substance added to air that causes the decline in the quality of air is called air pollutant. The different air pollutants include:

  • Oxides of sulphur such as SO2 and SO3.
  • Oxides of nitrogen such as NO and NO2
  • Greenhouse gases such as methane and carbon dioxide
  • Unburnt particles of carbon called soot.
  • Carbon monoxide
  • Dust and smoke

Question 10.
What is smog?
Answer:
The presence of oxides of sulphur, oxides of nitrogen, greenhouse gases such as methane and carbon dioxide, unburnt particles of carbon, dust and smoke in air mixes with fog to form smog in cold weather conditions. The smog formation reduces the visibility that harms the productivity because of the delay in travelling times, corrosion of metallic and marble structures.

Question 11.
Describe ozone as a chemical weed.
Answer:
Ozone is considered as a chemical weed because when on earth surface as a bluish gas, it is toxic to life but high up in stratosphere, it protects the life from the UV-rays present in solar radiations. The UV rays have harmful effects on human life because they are considered responsible for

  • Increasing incidences of skin bums and skin cancer.
  • Increasing cases of cataract.
  • Reducing crop production by more than 20%.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 12.
Which chemicals have reduced the thickness of ozone layer in stratosphere?
Answer:
Man made compounds called CFCs (Chlorofluro carbons) are very stable compounds. These compounds released from refrigerators and air conditioners cannot be degraded by any biological process. When they reach the ozone layer, the chlorine present in them combines with the monatomic oxygen produced on the dissociation of ozone to form stable compound. This continuously occurring reaction causes fire depletion of ozone layer.

Nitric oxide (NO) released in air also contributes to the depletion of the ozone layer.

Long Answer Questions

Question 1.
How the two biological processes respiration and photosynthesis are interrelated? Give an example to support your answer.
Answer:
The two biological processes, photosynthesis and respiration are interrelated because the end products of cellular respiration i.e. carbon dioxide and water are the raw materials in the process of photosynthesis and the end products of photosynthesis i.e. sugar and oxygen are the raw materials used in the process of cellular respiration.
Respiration,
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
Photosynthesis,
6CO2 + 12H2O + Solar energy → C6H12O6 + 6H2O + 6O2

Therefore, in green plants during early morning and later evening, no gaseous exchange takes place as at this time, rate of photosynthesis equals the rate of respiration taking place in their cells.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 2.
Explain the water cycle with the help of a diagram.
Answer:
The water cycle involves

  • the evaporation of water in form of its vapours from the earth surface and hydrosphere under the heating effect of solar radiations.
  • the condensation of water vapours high up in atmosphere to form clouds containing water in its condensed form of water droplets.
  • the precipitation that returns the water back to earth in form of rain, hail or snow.

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources 1

Question 3.
Draw and explain nitrogen cycle in nature.
Answer:
Nitrogen is almost chemically inert gas but is the major constituent of the atmospheric air. (78%) It cannot be directly used by the plants and animals but is essential for all living organisms being the major constituent of proteins and nucleic acids. Therefore, the atmospheric nitrogen is first fixed in form of compounds that can easily be absorbed by the plants.

In nature nitrogen fixation occurs in three possible ways. These are

  • Atmospheric fixation, when lightning occurs during thunder storm. The nitrogen combines with oxygen to form its oxide or nitrogen combines with hydrogen to form ammonia. These oxides being water soluble reach the earth with rainwater.
  • Biological fixation which is carried out by the free nitrogen fixing cyanobacteria like nostoc and anabena or by the bacteria named Rhizobium present in the root nod-ules of legume plants.
  • Industrial fixation involves the formation of nitrogen compounds by chemical fertilizer producing companies.

The nitrogen compounds present in soil in form of nitrites undergo nitrification by bacterial action to form nitrate ions that are absorbed by the plants and used up in synthesis of proteins and nucleic acids. From plants, the nitrogen compounds reach animals in form of amino acids and nitrogenous bases for their growth.

The plant and animal waste or their dead parts later undergo either decomposition to produce nitrite or nitrates or undergo bacterial denitrification to release the nitrogen in gaseous state in nature.
NCERT Solutions for Class 9 Science Chapter 14 Natural Resources 2

Question 4.
How is carbon cycle completed in nature?
Answer:
Carbon is incorporated into plants by process of photosynthesis. The process converts the gaseous carbon dioxide present in atmosphere or dissolved in water into glucose molecules. These molecules are the source of energy after their oxidation in the process of respiration. The process involves the release of carbon dioxide back in the atmosphere.

The compounds of carbon in different forms of carbohydrates, proteins and fats passes into animals for their survival.

The process of combustion of fuels also adds carbon dioxide to the atmosphere. The combustion involves the oxidation of compounds of carbon or carbon alone to produce energy in the form of heat and light. A small percentage of carbon in gaseous state is also released on the decomposition of organic matter by decomposers. A small percentage of carbon dioxide dissolved in water is also involved in formation of carbonates that are used by aquatic animals to make shells.

Hence, carbon in form of carbon dioxide cycles in nature between living organisms and atmospheric air.
NCERT Solutions for Class 9 Science Chapter 14 Natural Resources 3

NCERT Solutions for Class 9 Science Chapter 14 Natural Resources

Question 5.
Explain the oxygen cycle in nature.
Answer:
Oxygen gas is very important for most of the living organisms and is also abundantly available in atmospheric air, 21% by volume of the total atmospheric air. It is also present in form of its compounds in lithosphere such as metallic oxides and form of oxides of carbon, sulphur and nitrogen in air. In living organisms, it is the major constituents of essential organic compounds like carbohydrates, fats, etc.

In atmosphere, the oxygen is used in three processes i.e. respiration, combustion and formation of oxides. The used oxygen is returned to atmosphere by the process of photosynthesis in which it is released as the end product.
NCERT Solutions for Class 9 Science Chapter 14 Natural Resources 4

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