Monday, 8 July 2019

10th Chemistry Notes Chapter 6 The Atmosphere

10th Chemistry Notes Chapter 6 The Atmosphere
The 10th Chemistry Notes Chapter 6 The Atmosphere pdf ebook download is available at this page but you can also read the chemistry notes class 10 chapter 6 The Atmosphere online.

Q.1 What is meant by atmosphere?
 Ans. Atmosphere is the envelope of different gases around the Earth. It extends continuously from the Earth's surface outwards without any boundary. About 99% of atmospheric mass lies within 30 kilometers of the surface and 75% lies within the lowest 11 kilometers.
Q.3 What is the difference between primary and secondary pollution.
 Ans. Primary pollutants are the waste or exhaust products driven out because of combustion of fossil fuels and organic matter. These are the oxides of sulphur (SO, and SO): oxidescarbon (CO2 and CO): oxides of nitrogen (specially nitric oxide NO): hydrocarbon (CH) ammonia and compounds of fluorine.
 Secondary pollutants are produced by various reactions of primary pollutants. These are sulphuric acid, nitric acid, hydrofluoric acid, ozone and peroxy acetyl nitrate (PAN)
Q.4 What are the sources of CO2 and CO?
 Ans.
 (a) Both of these gases are emitted due to volcanic eruption and decomposition of organic matter naturally
 (b) The major source for the emission of these gases is combustion of fossil fuels (coal.
 petroleum and natural gas). Fossil fuels burned in combustion engine of any type of automobile, kiln of any industry, or open air fires emit CO and CO (C) Forest fires and burning of wood also emit CO2 and CO. Especially, when supply of oxygen is limited, emission of CO dominates
 Q.5 Why converters should be used in automobile exhausts?
 Ans. Converters should be used in automobile exhaust so that they convert Co to CO, and oxides of nitrogen NO to N before it enters in air.
Q.6. Write importance of C02 to life on earth.
 Ans. CO2 is the life gas' for plants. CO, absorbs infrared radiations emitted by the Earth Although CO2 is negligible as compared to N and O, yet its heat retaining capacity is nandos. Without CO2 life on earth would have been impossible.
 Q.7. Write occurrence of sulphur compounds in the atmosphere.
 Ans. Naturally occurring sulphur containing compounds are emitted in the bacterial decay of organic matter, in volcanic gases and forest fires. But the concentration of sulphur containing compounds in the atmosphere because of natural resources is very small as compared to the concentration of those compounds emitted by fossil fuel combustion in automobiles and industrial units. About 80% of the total SO: is released by the combustion of coal and petroleum products.
 Q.8 How SO2 and SO are formed? How these gases cause air pollution?
 Ans. Fossil fuels contain Sulphur Fossil fuels are burned to produce energy The sulphur in the fuel forms oxides of sulphur. SO, and SO Oxides of sulphur escape into the air. They are air pollutants Oxides of sulphur dissolve in water and form Acid Rain.
 That falls on the earth
Q.9 What are the effects of SO, gas? Also writes its properties / characteristics.
 Ans. It cause suffocation, irritation SO, forms sulphuric acid which damages buildings and vegetations. SO2 is a colourless gas having irritating smell.
 Q.10 How to control pollution because of sulphur?
 Ans. To control pollution because of SO. It is necessary to remove sulphur from fossil fuels before they are burnt
 Q.11 How nitric oxide is produced in air?
 Ans. naturally occurring oxides of nitrogen, mainly nitric oxide (NO), is produced by the electrical lighting in air.
Q.12. How nitric oxide is produced by the combustion of fossil fuels?
 Ans. Combustion of fossil fuels in internal combustion engine in thermal power stations and factories where huge amount of coal is burnt, NO is formed by the direct combination of nitrogen and oxygen
 Q.14 How NO and NO2 are formed? How these gases causes air pollution.
 Ans. Nitrogen in the air is normally un-reactive At high temperature it reacts with oxygen to form oxides of nitrogen. NO & NO These gases escape into the air. They are pollutants Oxides of nitrogen dissolve in water and form Acid Rain. That falls on the earth
 Q.15 How the mixture of NO and NO2 gases are represented? Write their effects.
 Ans. Mixture of these gases represented as NO, enter in the air through automobile exhaust and chimneys of thermal power station and factories. It irritates breathing passage. These oxide form nitric acid combining with water vapours in air. Nitric acid is a component of acid rain which damage soil, animals,plants and aquatic life.
Q.17 What is meant by ozone? How it is formed in atmosphere?
 Ans. Ozone is an allotropic form of oxygen consisting of three oxygen atoms. It is formed in atmosphere by the association of an oxygen atom with an oxygen molecule in the mid of stratosphere
 Og)
 0) + 020
 Q.18 What is meant by Ozone? Where ozone layers exist in atmosphere?
 Ans. Ozone is an allotropic form of oxygen. It is represented by O Ozone is present throughout the atmosphere. But its maximum concentration called ozone layer lies in stratosphere region about 25 to 30 km away from the Earth's surface.
 Q.19 How ozone layer protects our earth?
 Ans. Ozone layer surrounds the globe and protects Earth like a shield from harmful ultraviolet radiation of sunlight as shown in figure otherwise, ultraviolet radiations would cause skin cancer. Thus ozone layer is stratosphere is beneficial for life on Earth.
Q.21 What is meant by incineration?
 Ans. Incineration is a waste treatment process that involves the burning of solid waste at high temperature between 650°C to 1100 C in incinerators
 Q.22 What is the function of incinerator?
 Ans. Incinerators reduce the solid mass of the original waste by 80-85% and convert the waste materials into ash, flue gas and heat. Although, the volume of solid waste is reduced effectively by incineration, it produces highly poisonous gases and toxic ash.
 Q.23. Write composition of flue gas
 Ans. The flue gas includes dioxins. furans, sulphur dioxide, carbon dioxide, carbon monoxide, hydrochloric acid and a large amount of particulate matter.
 Q.24 What is meant by filtration?
 Ans. Filtration is separation of insoluble solid particles (sand, clay, dust or precipitates) from a liquid. It is carried out by filtering a mixture.
Q.25 What is the difference between pollutant and contaminants?
 Ans. The pollutants are those substances which cause pollution. While contaminants are those substance that make something impure
 Q26. What is meant by air pollution? Write its effects.
 Ans. The harmful substances present in air are called air pollutants. Even a beneficial substance beyond a specific concentration may be harmful. Air pollutants change the weather, badly affects the human health. damage the plants and destroy buildings
Q.27 What do you mean by atmosphere?
 Ans Our planet Earth has four natural systems: lithosphere, hydrosphere. atmosphere, and biosphere. So, atmosphere is the natural system of our planet Earth. It can be defined as Atmosphere is the envelope of different gases around the Earth. It extends continuously from the Earth's surface outwards without any boundary.
Q.29 Name the major constituents of atmosphere is maintained?
 Ans. The major constituents of troposphere are as follows:
 (a) Nitrogen (b) Oxygen
 These two gases comprises 99% by volume of the Earth's atmosphere.
 Q.30 How the temperature of atmosphere is maintained?
 Ans. CO2 and water vapours are present in atmosphere. Yet these are in low concentration but play an important role in maintaining temperature of atmosphere. Because both these gases allow visible light to pass through but absorb infrared radiations emitted by the Earth's surface. So, temperature of atmosphere is maintained
 Q.31 Where the ozone layer exists?
 Ans. Ozone layer exist in mid stratosphere.
 Q.32 Why the temperature of upper stratosphere is higher?
 Ans. Because ozone in the upper layer absorbs high, energy ultraviolet radiations from the sun, it raises the temperature of stratosphere. That is the reason temperature of upper stratosphere is higher
 Q.33 What do you meant by an air pollutant?
 Ans. The harmful substances present in air are called air pollutants.
 For example: Carbon monoxide CO
 Q.34 Name three primary air pollutants.
 Ans. (i) Hydrocarbon (CH) (ii) Ammonia (NH)
 (i) Oxides of nitrogen (NO)0.36 Why CO2 is called a greenhouse gas?
 Ans. Carbon dioxide is called as a greenhouse gas because it forms a layer around the Earth like an envelope. It allows the heat rays of the sun to pass through it and reaches upto the Earth but does not allow the IR radiations to pass through. So, it acts like a glass and also called as a greenhouse gas.
 Q.37 Why the flood risks are increasing
 Ans. CO is an air pollutant. It is a health hazard being highly poisonous gas. Being colorless and odourless, it presence cannot be noticed easily and readily. When inhaled, it binds with the hemoglobin most strongly than that of oxygen. Thus hindering the supply of oxygen in body. Exposure to higher concentration of CO causes headache and fatigue. If inhaled for a longer time it results in breathing difficulties and ultimately death. It is the reason burning is not allowed in closed places, it is advised to switch off coal or gas heaters, cooking range etc., before going to sleep.
 Q.38 How sulphur containing compounds are emitted naturally?
 Ans. Naturally occurring sulphur containing compounds are emitted in the bacterial decay of organic matter, in volcanic gases any forest fires.
Q.39 How combustion of fossil fuels in internal combustion engine produces oxides of nitrogen.
 Ans. Combustion of fossil fuels in internal combustion engines, in thermal power stations and factories where huge amount of coal is burnt, NO is formed by the direct combination of nitrogen and oxygen.
 0.40 How acid rain is produced?
 Ans. Acid rain means presence of excessive acids in rain water. This rain is produced when normal rain water dissolved oxides of sulphur and nitrogen in air. Rain water converts SO2 into H SO, and NO to HNO2 and HNO:. These acids reduces the pH of rain water upto 4.
 Thus acid rain formed on dissolving acidic air pollutant such as SO and NO, in rain water.
 Q.41 Why acid rain damages buildings?
 Ans. Acid rain attacks the calcium carbonate present in the marble and limestone of buildings and monuments. Thus, these buildings are getting dull and eroded day by day.
Q.42 How aquatic life is affected by acid rain?
 Ans. Water Pollution: Acid rain on soil and rocks leaches heavy metals (Al, Hg, Pb. Cr etc.) with, it and discharges these metals into rivers and lakes. This water is used by human beings for drinking purpose. These metals accumulate in human body to a toxic level. On the other hand, aquatic life present in lakes also suffers because of high concentration of these metals. Especially high concentration of aluminium metal clogs the fish gills. It causes suffocation and ultimately death of fish
 Q.43 Why plants are dying day by day? Comment.
 Ans. Damages Leaves of Trees and Plants: Acid rain directly damages the leaves of trees and plants, thus limiting their growth. Depending upon the severity of the damage, plants growth can be hampered. Plants ability to bear cold or diseases reduce to get it die.
 Q.44 Justify, ozone is beneficial for human beings.
 Ans. Ozone is present throughout the atmosphere. But is maximum concentration called ozone layer lies in stratosphere region about 25 to 30 km away from the Earth's surface. This layer surrounds the globe and protects Earth like a shield from harmful ultraviolet radiations of sunlight. Otherwise ultraviolet radiations would cause skin cancer. Thus ozone layer in stratosphere is beneficial for life on the earth.

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