JEE MAIN 2020 NEWS
NATIONAL LEVEL ONLINE TEST
Environment means surroundings. Surrounding constitutes air, water, soil, plants, animals and atmosphere everything around us. So, environmental chemistry means, the study of physical, biological, chemical and social interaction with the surrounding or simply. Considered a relatively easier chapter in JEE Main Chemistry Syllabus, it is a sure shot scoring one as a couple of questions are necessarily put forward from it.
There are two components in our environment.1: Biotic Components: living Organism 2. Abiotic Component: non-living Organism t: Air, Water, Soil. Our certain undesired activities are contributing to the destruction of our environment, and very soon, a time will come when the earth will not be able to sustain life. Now here we are trying to throw some light on some of the essential aspects of environmental chemistry under the following headings: -
Pollution is an undesirable change happens to the surroundings, maybe in physical, biological or in a chemical form which has a harmful impact and creates a potential hazard for any living organism.
Pollutants are substances which cause pollution. It can be substantial, liquid or gaseous substances present in any form in nature and might be produced due to some human activities or due to some natural phenomenon. Example:
Pollutants can classify into Biodegradable & Non-biodegradable: -
Pollutants like the mixture of particles and gases, when present more than a permitted level in the surrounding air is called air pollution. It harms the living organism. The effects of air pollution can range from higher disease risks to rising temperatures. Some examples of common pollutants are Soot, smoke, mould, pollen, methane, and carbon dioxide.
1. Gaseous air pollutants: Gaseous air pollutants are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.
2. Particulate pollutants: Particulate pollutants are dust, mist, fumes, smoke, smog, etc.
Carbon monoxide (CO): Carbon monoxide is formed by incomplete burning that is burning with less supply of oxygen, carbon monoxide is formed. So it is formed by incomplete combustion of fuel in industries. Methane is produced by the decomposition of organic matter and methane also produces carbon monoxide by a chemical reaction in the atmosphere
Example: Haemoglobin in blood carries oxygen from the lungs to a different part of the bodies. presence of carbon monoxide in the air prevents oxygen to get attached to haemoglobin this is why carbon monoxide is a poisonous gas. carbon monoxide creates oxygen transportation problem in the blood. Inhaling carbon monoxide gives headache, nausea, vomiting.
Sulphur dioxide ( SO2) and sulphur trioxide ( SO3) are two gaseous pollutants; Coal has little sulphur init. so when it burns it produces sulphur dioxide. Apart from Sulpher dioxide in air changes to sulphur trioxide another gasses oxide of sulphur, both can change to very reactive acids in the presence of water vapour in the air. Sulpher is produced from thermal power plants, factory boilers, coal-burning at home. Example: The inhalation of sulphur dioxide causes respiratory ailments and it aggravates respiratory diseases like asthma, bronchitis, irritation in eyes etc.
Oxides of nitrogen NO2 and NO are obtained by combustion of coal, gasoline. natural gas. petroleum refining, chemical industries and tobacco smoke. In the upper atmosphere. these are emitted by high flying jets and rockets. All are responsible for increasing the level of oxides of nitrogen in the air. Breathing NO2 causes chlorosis to plants and chronic lung conditions leading to death in human beings. These oxides destroy ozone layer
(iv) Smoke, dust These are obtained in cement works, iron and steelworks. gas works, power generating stations. Coal miners suffer from black lung disease and textile workers suffer from white lung disease.
Ammonia It is produced by fertilizer works.
Mercaptans These are obtained from oil refineries. coke ovens etc.
Zn and Cd These are obtained from zinc industries.
Freon (or CFC’8) Their source is a refrigerator.
The rainwater usually has a 5.6 pH due to the presence of ions of Hydrogen formed by the reaction of rainwater with carbon dioxide present in the atmosphere. But when the pH value falls below 5.6 Acid rain occurs.
H2O(l) + CO2(g) ——> H2CO3(aq)
Source: Burning of fuels such as coal and oil which produces sulphur dioxide and nitrogen oxides.
After oxidation of SO2 and NO2 and their reaction with water are major contributors to acid rain. As polluted air usually contains particulate matter that plays a major part in the oxidation of components.
The earth’s surface has a capacity to absorb about 75 % of the solar energy reaching the earth. The absorbed solar energy increases the temperature of the surrounding environment. The rest of the heat is absorbed back by the atmosphere. But some of the heat is trapped in the atmosphere due to presence of various gases like carbon dioxide, methane, ozone; chlorofluorocarbon compounds (CFCs) and water vapour.
Thus, they contribute to the heating of the atmosphere. This causes global warming. But it is important to realize that these gases are also responsible for sustaining life on this earth as they trap the requisite amount of solar energy for survival. The increased amount of greenhouse gases is raising the temperature of the earth’s atmosphere which may eventually result in the melting of polar ice caps and consequently submerge the coastal landmass.
Smog is a mixture of mainly smoke, dust particles and small drops of fog. Smog is two types.
1. Classical Smog: -It occurs in a climate which is cool and humid. It is also called as reducing smog made up of smog, sulphur dioxide and fog
2. Photochemical Smog: - It occurs in a warm, dry and sunny climate. photochemical smog results from the action of sunlight on unsaturated hydrocarbons & oxides of nitrogen produced by automobiles & factories. It is also called oxidizing smog. It consists of formaldehyde, acrolein, nitric oxide, ozone, and other chemical gases.
The molecule comprising three oxygen atoms; O3 it is formed when u-v rays in the upper atmosphere split oxygen atoms :
When an oxygen molecule splits into atoms, each atom combines with the undissociated molecule of oxygen to form ozone.
ozone protects us from u-v radiations as it doesn't allow the rays to enter earth atmosphere that if they enter they may harm us.
Ozone layer depletion is believed to be the result of the release of chlorofluorocarbon compounds (CFCs), these compounds are found in refrigerators, air conditioners, in the production of plastic foam and are also used by the electronic industry for cleaning computer parts etc.
CFCs when released in the atmosphere, they mix with the normal atmospheric gases and gradually reaches the stratosphere and they get broken down by powerful UV radiations, releasing chlorine free radical.
CF2Cl2(g) —-UV——> Cl. (g) +CF2Cl. (g)
Cl. (g) + O3 (g)————>ClO.(g) + O2(g)
ClO.(g) + O(g)————–> Cl.(g)+ O2 (g)
This way, the chlorine radicals are continuously regenerated and causes the breakdown of the ozone layer. Thus, CFCs are transporting agents for continuous generating chlorine radicals into the stratosphere and damaging the ozone layer.
Water is essential for life and pollution of water originates from certain human activities like disposal of waste materials into the water bodies etc
Major Water Pollutants:
The process of making the water suitable for its application or returning its natural state is called Water treatment thus, water treatment is required before and after its application. The required treatment depends on the application. Water treatment involves science, engineering, business, and art. The treatment may include mechanical, physical, biological, and chemical methods. As with any technology, science is the foundation, and engineering makes sure that the technology works as designed.
Effects of Impurities in Water
(a) Fluorides Mottling of teeth enamel, above 1 mg/L fluoride causes fluorosis.
(b) Sulphates of Na, K, Mg cause diarrhoea.
(c) Lead It damages the kidney, liver, brain and central nervous system.
(d) Cadmium and mercury They cause kidney damage.
(e) Zn It causes dizziness and diarrhoea.
(f) Arsenic It can cause cramps and paralysis.
(g) Phosphates from fertilizers They promote algae growth and reduce dissolved oxygen concentration of water. This process is known as eutrophication.
Soil pollution means contamination of soil and degrades the soil by using various chemicals and other human activities
Soil pollution is a global problem. causing a harmful effect on the soil and the environment
As we know sound is an important means of communication and is a necessary part of human life. Noise is referred to as undesirable and unwanted sound that is usually unwanted. Noise affects both human health and mind and agencies is a pollution problem and contributes towards the general deterioration of environmental quality. They are caused by factories and industries. mode of transport, social functions etc
The acquisitive nature of man temped him to exploit nature, As a consequence of ruthless exploitation of the natural environment is deteriorated day by day. So, man as a social partner of the environment should involve itself in activities for preservation, development and promotion of the overall environment.
Practice with JEE Main Question Paper
What is the greenhouse effect? How does it affect the global climate?
It is the phenomenon in which the earth’s atmosphere traps the heat from the sun and prevent it from escaping into the outer space. Greenhouse gases such as CO2, CH4, ozone, chlorofluorocarbon compounds and water vapour in the atmosphere result in climate changes .heats the plants by the heat emitted by the plants in the form of infrared radiation cannot pass through the glass or plastic panes. As a result of inside temperature increases.
What is acid rain? How is it harmful to the environment?
What do you mean by green chemistry? How will it help in decreasing Environmental Pollution?
Green chemistry involved in the design, development and implementation of chemical products that reduce or eliminate the use and generation of harmful substances hazardous to human health and environment. The release of different harmful chemicals causes pollution Thus the goal of green chemistry is to promote the development of products and processes that reduce or eliminate toxic substances associated with the design, manufacture and use of hazardous chemicals. For example, through the efforts of green chemists, H2O2 has replaced tetrachloromethane and chlorine gas in drying and bleaching of paper. CO2 has replaced CFCs as blowing agents in the manufacture of polystyrene foam sheet.
Statues and monuments in India are affected by acid rain, how?
The air around the statues and monuments in India contains relatively high levels of the oxides of sulphur and nitrogen. This is due to a large number of industries and power plants in nearby areas. The problem has further arisen due to the use of poor quality of coal, kerosene and firewood as fuel for domestic purposes. The states acid rain affects for marble of these statues and monuments. CaCO3+H2SO4 ‐> CaSO4+H2O+CO2 As a result, this away and marble is getting discoloured and lustreless.
What are harmful effects as depletion of the ozone layer?
1) The ozone layer protects the earth from the sun's harmful UV radiation, as the layer gets depleted more radiations will enter the earth’s surface. Those radiations are harmful because they lead to skin cancer and sunburns.
2) They cause the death of many phytoplankton’s which lead to a decrease in fish productivity.
3) Increase in UV radiation decreases the moisture content of the soil and damages both plants and fibres.
1. Biochemical Oxygen Demand (BOD): The measure of the total contamination caused by compounds which can be oxidised in the presence of microorganisms. The BOD is taken as a realistic measure of water quality - clean water would have a BOD value of less than 5ppmwhereas highly polluted river would have a BOD value of 17ppm or more.
2. Eutrophication: It is a result of excessive disposal of chemicals that leads to excess growth of algae in water bodies that are water bloom results in oxygen depletion and aquatic life suffers a lot because of this effect.
3. Global warming: the concentration of certain gases like carbon dioxide, methane etc in the air increases gradually because of which infrared rays gets trapped in it and it leads to an increase in the overall temperature of the earth is called global warming.
Candidates can make a study plan for the last 45 days remaining for JEE Main 2020. During the last days, most of the candidates are almost done with their syllabus and are planning to start the revisions. Your revisions also need to be planned so that you can cover all the topics. So here we have prepared a 45 days study plan which is as follows :
|July 5 to 15, 2020||Physical Chemistry has the most weightage in JEE Main Chemistry. Study important chapters from this section such as Atomic Structure, Electrochemistry, and Equilibrium first. Then, move on to study the chapters with lesser weightage like Surface Chemistry and Solid State. Choose two topics everyday and go through them. Revise the basics well. Use NCERT books.|
|July 16 to 26, 2020||Study Organic Chemistry. Pay more attention to important chapters such as Aromatic Compounds, Alkyl Halides, Alcohol, and Ether. Then, move on to study less important chapters such as Biomolecules and Carbonyl Compounds. Use NCERT books.|
|July 27 to August 8, 2020||Study Inorganic Chemistry. Start by studying the most important chapters like Chemical Bonding, p Block, and s Block. Then study less important chapters like Metallurgy and Qualitative Analysis. Use NCERT books.|
|August 9 to 20, 2020||Revise all the formulas and important concepts. Solve as many previous year’s papers as you can. Pick up questions from the Chemistry section and attempt them as fast as you can (within 45 minutes-1 hour).|
|August 21 to 31, 2020||Attempt mock tests everyday. Do one final revision of weak areas and important tricks and tips.|
|September 1 to 6, 2020||Research the analysis of the ongoing papers.|
During the preparation phase, you might feel demotivated in terms of your preparation.so try to avoid that. .People tend to lose marks if they are nervous or not very confident on the exam day. Disconnect all communication from social media in the last few days. Proper sleep will calm your nerves. Also, music would be a great help.