We have completed the NCERT/CBSE Solutions chapter-wise for Class 9 Science Chapter 14 Natural Resources with Answers by expert subject teacher for latest syllabus and examination. Prepare effectively for the exam taking the help of the Class 9 Science NCERT Solutions PDF free of cost from here. Students also can take a free NCERT Solutions of Natural Resources. Each question has right answer Solved by Expert Teacher. Download the Science NCERT Solutions with Answers for Class 9 Science Pdf and prepare to help students understand the concept very well.
NCERT Solutions for Class 9 Science Chapter wise
Questions
Q1. How is our atmosphere different from the atmospheres on Venus and Mars?
Answer: 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%.
Q2. How does the atmosphere act as a blanket?
Answer: It maintains the consistency in temperature throughout the day making it a comfortable place to stay.
The ozone in the atmosphere is responsible for maintaining the temperature without letting the harmful ultra-violet ray affect.
Q3. What causes winds?
Answer: Winds are basically caused by heating of air in certain parts. The hot air rises upwards. This creates an area of low pressure. Cooler air from adjacent higher pressure areas passes into this area. This creates wind. The factors which control movement of winds in different directions in different parts of the earth are
- Uneven heating of land in different parts of earth
- Differences in heating and cooling of land and water.
- Barrier of mountains
- Rotation of earth.
Q4. How are clouds formed?
Answer: Due to the heat of the sun, a huge volume of water evaporates from various water bodies during the day and rises into the air. The air in the atmosphere heats up as a result of this. When water vapour-carrying air rises, it expands and cools. Water droplets develop as a result of the condensation of water vapour. Clouds arise as a result of the production of water droplets.
Q5. List any three human activities that you think would lead to air pollution.
Answer: The following three human activities would lead to air pollution:
(i) Burning of fossil fuels such as coal and petroleum
(ii) Industrialization
(iii) Deforestation
Questions
Q1. Why do organisms need water?
Answer: The organisms need water:
- For different cellular process.
- For transportation of substance from one place to another inside the body.
Q2. What is the major source of fresh water in the city/town/village where you live?
Answer: – Rainfall
- Underground water from wells
- Water sources like pond, river, and lake
- Snowfall
Q3. Do you know of any activity which may be polluting this water source?
Answer: Dumping of industrial wastes from where pollutants seep into soil to reach ground water (sewage and industrial effluents in case of canal or river water).
Questions
Q1. How is soil formed?
Answer: Various processes and factors help in the formation of the soil. The major plays by the sun, water, wind, and living organisms in soil formation.
Sun: During the day, the sun warms rocks, causing them to expand. These rocks cool and contract throughout the night. Since all parts of the rock do not expand and contract at the same rate, this causes the formation of cracks which lead to the breaking up of huge rocks into smaller pieces.
Water: Water contributes to soil formation in two ways. Water pours through the cracks in the rocks caused by the sun’s heat. When this water freezes, it increases in volume. As a result, the size of the holes grows as well. The weathering of rocks is helped by this. Hard rocks are worn away over time by flowing water. Large and tiny rock fragments are frequently carried downstream by fast-moving water. These rocks scrape against one other, causing the rocks to crumble. Running water carries these smaller particles away and deposits them along its course.
Wind: Strong winds move rocks away, causing them to rub together. As a consequence, rocks are broken down into smaller and smaller bits.
Living Organisms: Some organisms, temperature rise, too, for example, Lichens, help in the development of soil. Lichens can also be found on rocks. Lichens emit specific chemicals during their development, which cause the rock surface to powder down, creating a thin coating of soil. Other tiny plants, such as moss, can now grow on this surface, causing the rock to break apart even further. The roots of large trees can occasionally become caught in cracks in the rocks, and as the roots get larger, the crack expands.
Q2. What is soil erosion?
Answer: The blowing away or washing away of land surface by wind or water is known as soil erosion.
Q3. What are the methods of preventing or reducing soil erosion?
Answer: The methods of preventing or reducing soil erosion are:
- Plantation of tress and plants
- Prevention of deforestation
- Prevent excessive grazing
Questions
Q1. What are the different states in which water is found during the water cycle?
Answer: Water is found in all three states like
- A solid-state (Snow, ice)
- Liquid state (river water, underground water)
- Gaseous state (water vapour)
Q2. Name two biologically important compounds that contain both oxygen and nitrogen.
Answer: Proteins and nucleic acids.
Q3. List any three human activities which would lead to an increase in the carbon dioxide content of air.
Answer: hree activities that increase the amount of carbon dioxide in the atmosphere are:
- Emission from the vehicles
- Burning of fossil fuels
- Forest fires due to human activities, deforestation.
- What is the greenhouse effect?
Ans: A rise in the amount of methane, carbon dioxide, nitrous oxide etc. in the atmosphere would cause the average temperature to increase on a global level. This is called the greenhouse effect.
Q4. 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 green house effect. An increase in the content of such gases would lead to a situation of global warming.
Q5. What are the two forms of oxygen found in the atmosphere?
Answer: The two forms of oxygen found in the atmosphere are:
- Diatomic molecular form with chemical formula O2.
- Triatomic molecular form with chemical formula O3known as ozone.
Exercises
Q1. Why is the atmosphere essential for life?
Answer:- The atmosphere is constituted of various main gases like O2, N2, and CO2 which are the basis of living of microorganisms, plants and animals.
- Photosynthesis is due to earth’s atmosphere
- The constant temperature of the earth is the cause of the earth’s atmosphere
- Processes like respiration, burning, and combustion are due to the atmosphere
- The atmosphere is the main reason to restrict UV rays into the earth
Q2. Why is water essential for life?
Answer: Organisms need water due to following reasons :
- Component of Living Matter: Water is a major component (60-90%) of living matter.
Solvent: Water is a general solvent for chemicals found in the living world.
Reaction Medium: All biochemical reactions occur in the medium of water.
Transport: Substances are transported in the body of a living organisms only in the dissolved state.
Turgidity: Cells, cell organelles, tissues and other structures maintain their shape only when they contain sufficient water to make them turgid.
Q3. How are living organisms dependent on the soil? Are organisms that live in water totally independent of soil as a resource?
Answer: All living organisms are dependent on soil. Certain organisms rely on each other directly, while others rely on each other indirectly. Plants require soil to acquire nutrients and support. On the other hand, organisms depend on plants for food which is essential for life. Carnivores feed on animals, which in turn rely on plants for food,
whereas herbivores feed on plants directly. As a result, they are indirectly dependent on soil. Water-dwelling organisms are not dependent on the soil as a source of food. Minerals are required for the survival of aquatic plants. Rivers, rains, and other natural processes transport these minerals from the soil to aquatic bodies. Aquatic life is hard to envisage without the flow of minerals from the land to the water bodies.
Q4. You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Answer: he 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. Rain fall is measured by an instrument known as the rain gauge. Wind speed is measured by anemometers. There are various instruments used to measure humidity.
Q5. Write a note on how forests influence the quality of our air, soil and water resources.
Answer: Air:
- Forests help in purifying the air by absorbing all kinds of pollutants.
- Forests help in increasing the oxygen level in the air by absorbing carbon dioxide during photosynthesis.
- Transpiration helps to maintain the temperature of the surrounding and helps in the formation of clouds.
Soil:
- Plants in forest hold the soil thereby preventing soil erosion.
- Adds nutrients to the soil as a lot of vegetation present in the forest gets decomposed.
Water:
- Forest helps in bringing rain and increasing the level of water in underground levels
Q6. 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.
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