Our Natural Resources - Compulsory Test (17-02-2017) - Class 9 MCQ

Movement of air occurs due to difference in air pressure of two places. It is not influenced by rotation of earth, vaporization and condensation of water vapour and topography over which passes.

The envelop of air surrounding the surface of planets is called atmosphere. Earth, Venus and Mars all these planets have their own atmosphere.

The atmosphere of Venus and Mars planet consists of mainly carbon dioxide gas. Due to presence of higher amount of carbon dioxide gas temperature increases very high during day and low during night.

In atmosphere oxygen is found in form of ozone (O₃)(O₃)and oxygen(O₂)(O₂). Oxygen is found in lower layers and ozone in ozonosphere.

Biologically important compounds that contain both oxygen and nitrogen is protein and nucleic acid. These compounds contain oxygen and nitrogen besides carbon and hydrogen.

Atmosphere play very important role in temperature of earth. If there were no atmosphere surround the earth, then the temperature of the earth increase during day and decrease during night.

 

Major part of fresh water is located on mountain tops ans glaciers in form of ice caps and glacier. Major portion of water found on earth is salty and found in ocean and seas.

Rise is temperature of water due to addition of hot water into it is known as thermal pollution. Thermal pollution causes death of aquatic organisms.

Percentage of total water found as fresh water is only 2.5%. Out of this percent of water most are in form of ice caps and glaciers. The major portion of water is salty and found in ocean and sea.

Soil is mixture of sand particles, humus and other organic substances along with microbes. Different soil has particles of different size. Clay soil has smallest soil particles.

Soil erosion can be prevented by good plant cover. The root of plant binds the soil and prevents the soil erosion. Soil erosion occurs faster in bare lands with vegetation.

The process of breaking down large rock particles into small soil particle is called weathering. Wind causes weathering of rocks through abrasion on its surface.

Plants require water for all physiological processes. Water is present in soil as hygroscopic, gravitational and capillary water but water available for plant for absorption is capillary water.

Soil erosion is promoted by scarping of top soil, falling of trees, clean tilling and high speed wind.

Top soil is the uppermost fertile soil layer. Top soil contains humus, living organisms and soil particles.

 

To match the given options with the correct responses, we can analyze each statement and find the corresponding answer.
1) Prevention of soil erosion: This refers to the measures taken to protect the soil from being washed away or blown off by wind. The correct response is (D) Afforestation, as planting trees helps in preventing soil erosion.
2) Water borne disease: This refers to diseases that are caused by pathogenic microorganisms which are transmitted through contaminated water. The correct response is (A) Cholera, as it is a waterborne disease.
3) Mineral in soil: This refers to the various minerals present in the soil, which provide essential nutrients for plant growth. The correct response is (C) Weathering of parent rock, as the minerals in the soil are derived from the weathering of the parent rock.
4) Most fertile layer: This refers to the layer of soil that is richest in nutrients and supports plant growth. The correct response is (B) Top soil, as it is the uppermost layer of soil which is most fertile.
Therefore, the correct matching is:
A: 1-C, 2-B, 3-D, 4-A

Explanation:

The correct answer is C: (b) and (d) are correct.
Here is a detailed explanation of each option:
A. Raising forests: This option does not increase soil erosion. In fact, forests can help prevent soil erosion by providing a protective cover for the soil.
B. Overgrazing by animals: Overgrazing can lead to soil erosion because when animals consume too much vegetation, the roots of the plants are weakened, resulting in less protection for the soil.
C. Step farming: Step farming, also known as terrace farming, can help prevent soil erosion. By creating terraces on steep slopes, water runoff is reduced, allowing the soil to retain more moisture and preventing erosion.
D. Deforestation: Deforestation is a major cause of soil erosion. When forests are cleared, the protective cover provided by the trees is lost, leaving the soil exposed to the elements. Without vegetation to hold the soil in place, it can easily be washed away by rain or blown away by wind.
In summary, both overgrazing by animals and deforestation increase soil erosion. Step farming, on the other hand, helps prevent soil erosion. Therefore, option C is the correct answer.

Weathering of rocks occurs by:
- Lichens: Lichens are a symbiotic association between fungi and algae. They release acids that can break down rocks and minerals, causing weathering.
- Frost: Frost weathering occurs when water seeps into cracks in rocks and freezes. When water freezes, it expands and exerts pressure on the rocks, causing them to break apart.
- Fossil fuels: Fossil fuels are not directly involved in the weathering of rocks. However, the burning of fossil fuels releases pollutants into the atmosphere, such as sulfur dioxide and nitrogen oxides, which can contribute to acid rain. Acid rain can accelerate the weathering of rocks and minerals.
- Fungi: Fungi can contribute to the weathering of rocks through their production of organic acids. These acids can dissolve minerals and weaken the structure of rocks.
Answer: (a) and (b) are correct. Lichens and frost contribute to the weathering of rocks. Fossil fuels and fungi do not directly play a role in the weathering process.

Those substances that can be broken down into simpler forms by action of microbes are called bio-degradable substance, leaves, fruits and vegetables and mud are biodegradable substance. Plastic cannot be broken into simpler forms so, it is an example of non-biodegradable pollutant.

Water pollution is the addition of harmful substance is water that changes its chemical, Physical and biological properties. Water pollution causes eutrophication, pesticidal toxicity and bio magnifications.

Use of large amount of fertilizers and pesticides turns the fields barren after sometime, they affect the useful components form the soil and destroy the soil fertility. Fertilizers and pesticides are not eco-friendly.

The major cause of ozone layer depletion includes CFCs (Chlorofluro carbons) that are released from fridges and air conditioners. This gas breaks the ozone (O₃)(O₃) into free oxygen.

Water hyacinth can be exploited to control water pollution but reduce the oxygen in water. Corbett National park is in the state of Gujarat. Forest check flood and soil erosion. Cow dung cakes and woods are common source of energy in villages.

Ozone depleting substances (ODS) are those substances that deplete the ozone layer. These substances includes chlorofluorocarbons other gases.

Toxic chemical released by paper industry is Mercury. Mercury is used to decolorize the paper and make it smoother.

Long exposure of UV light to man cause skin cancer. Depletion of ozone layer allows ultraviolet rays to enter the earth surface that may cause skin cancer to human beings.

Lichens are used as indicator of pollution. Lichens do not grow in area having very high pollution. Lichens are sensitive to Sulphur dioxide gas present in polluted air

Ozone hole was first noticed over Antarctica in 1985. Through this hole, ultraviolet rays reach to earth. Xenobiotic or man-made substances may be biotic or abiotic.

To match the types of pollution with their correct responses, we can analyze the characteristics of each type of pollution and match them accordingly.
1. Water Pollution:
- Water pollution refers to the contamination of water bodies such as rivers, lakes, and oceans.
- The correct response for water pollution is "C - Eutrophication" because excessive nutrients in the water can lead to the growth of algae and other aquatic plants, depleting oxygen levels and harming aquatic life.
2. Air Pollution:
- Air pollution refers to the presence of harmful substances in the air, affecting the quality of the atmosphere.
- The correct response for air pollution is "B - Acid rain" because pollutants in the air, such as sulfur dioxide and nitrogen oxides, can combine with atmospheric moisture to form acids that fall as rain.
3. Soil Pollution:
- Soil pollution refers to the contamination of soil with toxic substances.
- The correct response for soil pollution is "D - Soil erosion" because soil erosion can lead to the loss of fertile topsoil due to factors such as wind, water, and human activities.
4. Thermal Pollution:
- Thermal pollution refers to the increase in temperature of water bodies caused by human activities.
- The correct response for thermal pollution is "A - Hot water" because the discharge of heated water from industrial processes or power plants can raise the temperature of nearby water bodies, disrupting aquatic ecosystems.
Therefore, the correct match is: A - 1-C, 2-B, 3-D, 4-A.

The correct match for the given options is:
A: 1-D, 2-A, 3-C, 4-B
Explanation:
1. Inexhaustible - This term refers to resources that cannot be depleted or used up.
- Match: 1-D (Solar energy)
2. Exhaustible - This term refers to resources that can be depleted or used up over time.
- Match: 2-A (Minerals)
3. Clean fuel - This term refers to fuels that produce minimal or no harmful emissions when burned.
- Match: 3-C (CNG)
4. Hot air - This term refers to air that is heated or warmed up.
- Match: 4-B (Winds)
Therefore, the correct match for the given options is A: 1-D, 2-A, 3-C, 4-B.