Environmental issues are rampant and need to be addressed immediately without any further delay. Awareness needs to be created among students regarding this. NCERT Exemplar Class 11 Chemistry solutions Chapter 14 include types of pollution and strategies to tackle these. We have often heard terms like environmental conservation, preservation etc. However, Environmental chemistry deals with chemical processes that influence chemical composition and speciation of air, water and soil. The chemical fate, mobility of contaminants etc are included in this chapter. NCERT Exemplar class 11 Chemistry chapter 14 solutions aims to condition students and prepare them to be calculative about the chemical compositions and contaminants freely mobile in the environment.
NCERT exemplar class 11 Chemistry solutions chapter 14: MCQ (Type 1)
Which of the following gases is not a greenhouse gas?
The answer is the option (i) CO
Explanation: Greenhouse gases have a property of not absorbing sunlight near the earth’s surface and not radiating back to the earth, CO shows the same traits; hence it is a greenhouse gas.
Which of the following statements is not true about classical smog?
(i) Its main components are produced by the action of sunlight on emissions of automobiles and factories.
(ii) Produced in cold and humid climate.
(iii) It contains compounds of reducing nature.
(iv) It contains smoke, fog and sulphur dioxide.
The answer is the option (i) Its main components are produced by the action of sunlight on emissions of automobiles and factories.
Explanation: Classical smog occurs in cold, humid climate due to the gases released by automobiles and factories. A mixture of smoke, fog and forms classical among.
Which of the following statements is wrong?
(i) Ozone is not responsible for green house effect.
(ii) Ozone can oxidise sulphur dioxide present in the atmosphere to sulphur trioxide.
(iii) Ozone hole is thinning of ozone layer present in stratosphere.
(iv) Ozone is produced in upper stratosphere by the action of UV rays on oxygen.
The answer is the option (i) Ozone is not responsible for the greenhouse effect.
Explanation: The contribution of to the greenhouse effect is about 8 to 10%. About 75% of solar energy is absorbed by the surface of the earth, and the rest is radiated back to the atmosphere. This heat traps gases like present in the atmosphere and adds to the heat of the atmosphere, causing global warming.
Which of the following statements about photochemical smog is wrong?
(i) It has high concentration of oxidising agents.
(ii) It has low concentration of oxidising agent.
(iii) It can be controlled by controlling the release of , hydrocarbons, ozone etc.
(iv) Plantation of some plants like pinus helps in controlling photochemical smog.
The answer is the option (ii) It has a low concentration of oxidising agents.
Explanation: Photochemical smog has a high concentration of oxidants since it comprises of , nitric oxide, formaldehyde, peroxyacetyl nitrate & acrolein. Photochemical smog causes serious health issues.
Which of the following practices will not come under green chemistry?
(i) If possible, making use of soap made of vegetable oils instead of using synthetic detergents.
(ii) Using for bleaching purpose instead of using chlorine based bleaching agents.
(iii) Using bicycle for travelling small distances instead of using petrol/ diesel based vehicles.
(iv) Using plastic cans for neatly storing substances.
The answer is the option (iv) Using plastic cans for neatly storing substances.
Explanation: Plastic is non-biodegradable and causes pollution. Hence, using plastic cans won’t come under green chemistry.
NCERT exemplar class 11 Chemistry solutions chapter 14: MCQ (Type 2)
Which of the following conditions shows the polluted environment.
(i) pH of rainwater is 5.6.
(ii) amount of carbon dioxide in the atmosphere is 0.03%.
(iii) biochemical oxygen demand 10 ppm.
The answer is the option (iii) biochemical oxygen demand 10 ppm and (iv) eutrophication
Explanation: Water having BOD less than 5ppm is considered as pure water, whereas water having BOD more than 5 ppm is considered as polluted. Therefore, BOD 10ppm will be highly polluted water.
Eutrophication is the process where the water is nutrient-rich but has a dense population; it kills animal life by depriving it of oxygen and results in loss of biodiversity.
The consequences of global warming may be _________.
(i) increase in average temperature of the earth
(ii) melting of Himalayan Glaciers.
(iii) increased biochemical oxygen demand.
The answer is the option (i) increase in the average temperature of the earth and (ii) melting of Himalayan Glaciers
Explanation: We know that the earth absorbed 75% of the solar energy and radiated the rest of it back to the atmosphere. This increases the global temperature and may result in the melting of glaciers and polar ice caps due to which the low-lying areas would be flooded. There will be an increase in infectious diseases like dengue, sleeping sickness, yellow fever, etc.
NCERT Exemplar Class 11 Chemistry Solutions Chapter 14: Short answer type
Greenhouse effect leads to global warming. Which substances are responsible for greenhouse effect?
There are various greenhouse gases out of which some are produced naturally, and some are man-made. Methane is a natural gas which is produced when vegetation is burnt or digested or rotted in the absence of oxygen. Paddy fields, coal mines, fossil fuel and rotten garbage, release large amounts of methane into the atmosphere.
Nitrous oxide occurs in the environment naturally but is increasing due to human activities day-by-day.
CFCs (Chlorofluorocarbons) are man-made and used in ACs. They contribute to greenhouse gases, too.
On the basis of chemical reactions involved, explain how do chlorofluorocarbons cause thinning of ozone layer in stratosphere.
Chlorofluorocarbons break down in the stratosphere by the powerful UV radiations and release free radicals of chlorine,
This chlorine radical reacts with stratospheric ozone and forms chlorine monoxide radicals and molecular oxygen,
Now chlorine monoxide radical produces with atomic oxygen produces more chlorine radicals.
Breakdown of ozone is caused by continuous regeneration of chlorine radicals. Therefore, we can say that CFCs are transporting agents who continuously generate chlorine radicals into the stratosphere and cause damage to the ozone layer.
What are biodegradable and non-biodegradable pollutants?
(i) Biodegradables are the pollutants that can be decomposed by bacteria, e.g., cow dung, waste of vegetables and fruits, etc.
(ii) Non-biodegradable pollutants are the one which cannot be decomposed by bacteria, e.g., Mercury, polythene, DDT, etc.
What are the sources of dissolved oxygen in water?
Dissolved oxygen in the water can be used by microorganisms to oxidise organic matter. It reaches water either through the atmosphere or due to photosynthesis carried out by aquatic plants. During the night, photosynthesis cannot take place due to the absence of sunlight, but the plants continue to respire and decrease the amount of dissolved oxygen present in water. The sources of dissolved oxygen in water are-
What is the importance of measuring BOD of a water body?
BOD is a measure of the amount of organic material present in water, in terms of how much oxygen it requires to break it down biologically. If the water has a value of BOD less than 5 ppm, it is considered as clean water, whereas highly contaminated water has the value of BOD of 17ppm or more.
Why does water cover with excessive algal growth become polluted?
Addition of fertilisers containing phosphate enhances the growth of algae in water which covers the surface of the water causing the foul smell, unattractive appearance, unfit for boating or swimming, as well as decreasing the amount of oxygen in the water which can be harmful to aquatic life.
How is ozone produced in stratosphere?
The UV radiations that fall on the ozone layer breaks the oxygen molecule into free oxygen(O) atoms; these free atoms of oxygen then react with molecular oxygen to form ozone.
NCERT Exemplar Class 11 Chemistry Solutions Chapter 14: Matching Type
Match the terms given in Column I with the compounds given in Column II.
(i) Acid rain occurs due to the presence of , and present in the atmosphere. They give carbonic acid, nitrous acid and sulphurous acid with water.
(ii) Hydrocarbon (unburnt fuel) and forms photochemical smog.
(iii) CO combines with haemoglobin to form carboxyhaemoglobin and doesn’t allow it to bind with oxygen again.
(iv) CFCs causes the depletion of the ozone layer by fastening the reverse process of formation of an oxygen molecule from ozone.
Match the pollutant(s) in Column I with the effect(s) in Column II.
(i) is poisonous, and even its los concentrations can cause respiratory diseases.
(ii) Oxides of nitrogen cause irritant red haze effect in the traffic and congested places.
(iii) ’s increases amounts in the air are responsible for global warming.
(iv) Excess nitrate in drinking water can cause methemoglobinemia, i.e., ‘blue baby’ syndrome.
(v) The maximum limit of lead concentration in drinking water is 50 ppb. Consuming it more than that can cause kidney damage.
Match the activity given in Column I with the type of pollution created by it given in Column II.
(i) Acid rain, smog formation, breathing problems, etc. are caused by .
(ii) Carbamates are biodegradable pesticides but can severely nerve toxins and cause harm to humans.
(iii) Synthetic detergent cause water pollution since they are non- biodegradable.
(iv) Gases released from factories can cause photochemical smog formation and cause damage to plants, water life, etc.
(v) CFCs present in the atmosphere are responsible for damaging the ozone layer.
Match the pollutants given in Column I with their effects given in Column II.
Explanation: Phosphates enhance the growth of algae in the water, which covers the surface of the water and reduces the concentration of oxygen in the water and thereby increasing the BOD level of water. This causes harm or may even prove fatal to animal life by depriving them of oxygen, and this subsequent loss of biodiversity is known as eutrophication.
Assertion (A): Excessive use of chlorinated synthetic pesticides causes soil and water pollution.
Reason (R): Such pesticides are non-biodegradable.
(i) Both A and R are correct and R is the correct explanation of A.
(ii) Both A and R are correct but R is not the correct explanation of A.
(iii) Both A and R are not correct.
(iv) A is not correct but R is correct
The answer is the option (i) Both A and R are correct, and R is the correct explanation of A.
Explanation: Pesticides are basically synthetic toxic chemicals with ecological repercussions. Its repeated use gives rise to pests which are resistant to it. Hence, as insect resistance of DDT increases, other organic pesticides like Aldrin and Aieldrin were introduced. Organic toxins and water-insoluble and non-biodegradable.
NCERT Exemplar Class 11 Chemistry Solutions Chapter 14: Long Answer Type
How can you apply green chemistry for the following :
(i) to control photochemical smog.
(ii) to avoid use of halogenated solvents in drycleaning and that of chlorine in bleaching.
(iii) to reduce use of synthetic detergents.
(iv) to reduce the consumption of petrol and diesel.
(a) Many techniques are used to reduced photochemical smog. If we reduce the primary precursors like NO2, the secondary precursors will be automatically reduced.
(b) Release of hydrocarbons and NO can be reduced by using catalytic converters in automobiles.
(c) Certain plants like Juniparus, Vitus, etc. can metabolise. No, hence, they should be planted.
(ii) Organic solvents are highly toxic, and hence, they should be used carefully. For bleaching cloth, is used rather than Cl2, viz. harmful.
(iii) Synthetic detergents are harmful; hence their daily use should be reduced, and instead, soap should be used, which is biodegradable.
(iv) CNG and LNG should be used instead of petrol and diesel oil because CNG and LNG are pollution-free.
Explain how does green house effect cause global warming.
The 'greenhouse effect' refers to the warming of climate that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere resemble glass in a greenhouse, allowing sunlight to pass into the 'greenhouse,' but blocking Earth's heat from escaping into space. The gases that contribute to the greenhouse effect include water vapor, carbon dioxide (CO2), methane, nitrous oxides, and chlorofluorocarbons (CFCs).
Also read - NCERT Solutions for Class 11 Chemistry
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Also read - NCERT Solutions for Class 11 Chemistry Chapter 14
Main Topics and Subtopics in NCERT Exemplar Class 11 Chemistry solutions Chapter 14 Environmental Chemistry
Class 11 Chemistry NCERT Exemplar solutions chapter 14 cover the following topics-
Causes of Water Pollution
International Standards for Drinking Water
Strategies To Control Environmental Pollution
Green Chemistry in day-to-day Life
What will students learn from NCERT Exemplar Class 11 Chemistry solutions Chapter 14?
Our planet is facing innumerable environmental problems and hence addressing these concerns becomes even more critical. Our apathy towards the environment stems out of ignorance. Keeping this view in mind, NCERT Exemplar solutions for Class 11 Chemistry chapter 14 Environmental Chemistry tries to enlighten students about environmental, air, water, soil pollution due to the chemical contribution at different levels of production. In addition to this, the chapter also provides methods of waste disposal and reduction.
NCERT Exemplar Class 11 Chemistry Solutions Chapter-Wise
Important topics to cover for exams from NCERT Exemplar Class 11 Chemistry solutions Chapter 14 Environmental Chemistry
The chapter is very simple as it includes topics that you have studied previously. However, along with these basic concepts, there are other terms that you might be unaware of. Let’s have a look at important topics in NCERT Exemplar Class 11 Chemistry solutions Chapter 14:
· Atmospheric pollution is a term we all are acquainted with. However, within atmospheric pollution there is Tropospheric Pollution, Stratospheric Pollution which is something new and will be dealt with in this chapter.
· We live in cities where we are completely detached to soil and have zero idea about its requirements. NCERT Exemplar class 11 Chemistry chapter 14 solutions throws light on this area. Use of pesticides, fertilizers etc and its aftermath is included.
· Water pollution and industrial waste are co-related. The make in India program is a good initiative if the waste disposal from the industries is prioritized before giving green signals to these industries.
· The only way to tackle the problem of pollution is to address it and realize the need of the time. Management of waste is a great solution to this problem and is looked at in this chapter
· Ever heard the word Green Chemistry? Sustainable chemistry or green chemistry focuses on production of substances that will minimize chemical disruption of the environment or rather of the ecosystem.
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