RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Rajasthan Board RBSE Class 11 Chemistry Chapter 14 Environmental Chemistry

RBSE Class 11 Chemistry Chapter 14 Text Book Questions

RBSE Class 11 Chemistry Chapter 14 Multiple Choice Questions

Question 1.
PAN means :
(a) Peroxy Aldehyde Nitrate
(b) Peroxy Ammonium Nitrate
(c) Peroxy acetyl Nitrate
(d) None of the above
Answer:
(c) Peroxy acetyl Nitrate

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 2.
Particulate air pollutant is :
(a) Chlorine
(b) Coal
(c) Ammonia
(d) All of the above
Answer:
(b) Coal

Question 3.
What is the reason of increase in temperature?
(a) Acid rain
(b) Nuclear Accidents
(c) Increase in heat at faster rate
(d) Green House Effect
Answer:
(d) Green House Effect

Question 4.
CFC’s are used in :
(a) Refrigerants
(b) Plastic formation
(c) In electrical appliances
(d) All of the above
Answer:
(a) Refrigerants

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 5.
Which of the following is not a green house gas?
(a) CO2
(b) CH4
(c) COCl2
(d) N2O
Answer:
(c) COCl2

Question 6.
In Ozone, number of Oxygen atoms are :
(a) 3
(b) 2
(c) 1
(d) 4
Answer:
(a) 3

RBSE Class 11 Chemistry Chapter 14 Very Short Answer Type Questions

Question 7.
What do you mean by Green House Effect?
Answer:
The blanketing effect of man made carbon dioxide, which increase the overall temperature of the Earth is called green house effect.

Question 8.
Which gases are responsible for acid rain?
Answer:
Oxides of nitrogen and oxides of sulphur are responsible for acid rain.

Question 9.
Which are the main gases which affect Ozone layer?
Answer:
Chlorofluoro-carbons (Freons) and related hydrocarbons affect ozone layer.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 10.
Write the composition of smog.
Answer:
The main components of smog are oxides of nitrogen, volatile organic compounds, tropospheric ozone and PAN (Peroxy acetyl nitrate).

Question 11.
Amount of which gas is maximum in atmosphere?
Answer:
Nitrogen (78.09%).

Question 12.
What are the major air pollutants?
Answer:
The major air pollutants are : (1) Gaseous air pollutants— SOx, NOx, CO, CO2 and hydrocarbons : (2) Particulate— Dust, smoke, mist, fog etc.

Question 13.
Which gases are responsible for green house effect?
Answer:
Carbon dioxide, Methane, Ozone, Nitrous oxide, Chloro fluoro carbon and water vapour.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 14.
How many types of water pollution are there?
Answer:
There are many types of water pollution because water comes from many sources. These are :

  1. Nutrients pollution
  2. Surface water pollution
  3. Oxygen depletion in water
  4. Ground water pollution
  5. Microbiological pollution
  6. Water pollution due to suspended matter
  7. Chemical water pollution
  8. Oil spoilage in water.

RBSE Class 11 Chemistry Chapter 14 Long Answer Type Questions

Question 15.
What are the main sources of air pollution?
Answer:
The main sources of air pollution are :
1. Natural sources :

  • Volcanic eruptions—release poisonous gases like
    SO2, H2S, CO etc.
  • Forest fires—release smoke and trace gases.
  • Decay of organic matter—release CH4.
  • Pollen grains, fungal spores, bacteria etc.

2. Manmade sources :

  • Population growth
  • Deforestation
  • Burning of fossil fuels
  • Automobile exhausts
  • Industrialization
  • Agricultural activities viz. use fo fertilizers, pesticides etc.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 16.
How smog formed and what are its effect?
Answer:
Formation of smog: Smog (photochemical smog) is produced as a result of reaction of sunlight on oxides of Nitrogen and Hydrocarbons emitted by vehicles and factories.
RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry 1
Ozone is a toxic gas and both NO2 and O3 are strong oxidising agents and can react with hydrocarbons emitted by vehicles to produce chemicals such as form aldehyde, acrolein and PAN (peroxy acetyl nitrate).
RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry 2

Effects of smog:

  • It causes corrosion of metals, stones, building materials, rubber and painted surface.
  • It causes irritation to eyes and nose.
  • Its high concentration causes headache, chest pain dryness of the throat, cough and difficulty in breathing.
  • It leads to cracking of rubber and damage to plant life.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 17.
What is acid rain? How it affects the pollution?
Answer:
Acid rain : Acid rain is the rain which contains chemical present in nature and other pollutants and falls on the Earth as slightly acid solution. Rain water is slightly acid with pH level between 5 and 6. If pH decreases below 5.6, then rain becomes acidic. This is caused by the presence of air pollutants like oxides of sulphur (SOx) and oxides of nitrogen (NOx), which mixed with rain water of form sulphuric acid and nitric acid. The formation of these strong acids make the rain acidic.
2SO2 + O2 + 2H2O ➝ 2H2SO4

Effects of acid rain :
Acid rain represents one of the major consequences of air pollution. It may cause extensive damage to materials, terrestrial ecosystem and aquatic ecosystem. The effects of acid rain are given below :

  • It causes damage to buildings and structural materials made from marble, limestone etc.
  • It causes death of aquatic animals.
  • It causes acidification of soil which decrease the fertility of soil
  • It deteriorates trees, forests and field.

Question 18.
What is Green House Effect? How it affects life?
Answer:
Green House Effect : It may be defined as “the progressive warming up of the Earth’s surface due to blanketing effect of man made carbon dioxide in the atmosphere.” It is the phenomenon due to which the Earth retains heat. The major gases responsible for green house effect, are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and chlorofluorocarbons (CFCs). Among these, CO2 is the most common gas which causes this effect.

Consequences of Green House Effect:
Its effects are detrimental to environment. These are given as below:

  • Due to green house effect, temperature of the Earth increases.
  • This may lead to melting of glaciers and polar ice caps.
  • The level of sea may rise which causes floods.
  • It affect the production of food crops.
  • The fertile land may become barren and aquatic life will be seriously affected.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 19.
What are the effects of depletion of Ozone layer?
Answer:
The effects of depletion of Ozone layer are given as below :

  • It creates burning sensation.
  • It causes skin cancer.
  • It causes destruction of life.
  • It causes swelling of skin.
  • It damages the plants.
  • It causes permature ageing of the skin. ’
  • It causes DNA mutation etc.

Question 20.
What is the impact of water pollution on plants?
Answer:
The impact of water pollution on plants is low crop yield. Due to contaminated water, the growing of crops will not be of good quality and quantity. It decreases the yield of crops.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 21.
What are industrial effluents and how it pollutes the environment?
Answer:
Industrial effluents include organic and inorganic chemical pollutants released from breweries, tanneries, paper mills and other industeries. They cause water pollution. Due to which, biological oxygen demand (B.O.D.) of water bodies increases. B.O.D. is the amount of oxygen required by microorganisms to decompose organic substances in water. More organic matter present in water leads to a high amount of B.O.D.

RBSE Class 11 Chemistry Chapter 14 Long Answer Type Questions

Question 22.
What are the sources of water pollution? What steps could be taken to prevent water pollution?
Answer:
Sources of water pollution :
There are following sources of water pollution :
1. Natural sources:

  • Pathogens which include bacteria and other organisns.
  • Faeces of organisms
  • Remains of plants and animal.
  • Minerals from mines etc.

2. Man-made sources :

  • Domestic sewage like rotten fruits, soaps, detergents etc.
  • Municipal sewage released from houses, public toilets, bathing etc.
  • Industrial wastes.
  • Industrial effluents.
  • Agricultural discharge like fertilizers, pesticides etc.

Prevention of water pollution :
The following steps could be taken to prevent water pollution :

  • Prohibition in bathing and washing of clothes in rivers and streams and also in discharging untreated or treated sewage in water bodies.
  • Judicious use of pesticides and fertilizers.
  • Re-use of water after treatment of waste water for irrigation and municipal purpose.
  • Regular monitoring of water bodies.
  • Use of waste water treatment plant in industries hospital etc.

Question 23.
Write short note on Industrial pollution.
Answer:
Pollutants from industries cause air, water and soil pollution. Class of industrial waste depends on the type of industry. Mostly, wastes come from industrial effluents. These contain organic substances, inorganic salts, solids, fertilizers etc. These are released in the form of heat, bacteria and pathogens. The places where rubber industries are situated releases chloride laden soluble wastes in environment.

Steel industires situated at Bhiwadi and other places release acid, phenol, cyanogen, limestone, oily substances, cyanide etc. in the from of pollutants. Acids, alkali, resins and petri-oils are released by Oil Refineries in the form of pollutants. The industries release various toxic substances like phenol acid and base in the form of pollutants. Pollutants like ammonium fluoride, potassium nitrate etc. are related from fertilizers industries.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 24.
What is Ozone layer? What are the reasons for its depletion? How the life on the Earth is affected by Ozone layer depletion?
Answer:
Ozone layer is found in Stratosphere. The area about 15-20 km above the sea is called Stratosphere. This layer protects us from the ultraviolet radiations (λ = 255 nm) coming from the Sun. This layer absorbs ultraviolet radiation. It acts as a blanket in the atmosphere.
O2(g) + O(g) ➝ O3(g)

Reasons for depletion of Ozone layer :
The main reason for the depletion of Ozone layer is the release of chlorofluorocarbons compounds (CFCs) in the atmosphere. These compounds are also called freons.

In the presence of UV radiations, CFCs are dissociated into nascent chloride and CIO free radical. There intermediates are chemically active and convert Ozone to oxygen. In this way, due to continuous formation of chlorine free radicals regularly dissociate ozone to oxygen.
RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry 3
…….. and so on
Effects of Ozone layer depletion :
The life of the Earth is affected by Ozone layer depletion as follows :

  • It causes burning sensation.
  • It causes skin cancer.
  • It causes destruction of life.
  • It causes swelling of skin.
  • It causes ageing of skin.
  • It causes DNA mutation etc.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 25.
Write a short note on air pollution and its prevention.
Answer:
Air pollution : Air pollution may be defined as “the presence of one or more contaminants such as fumes, dust, gases, mist, smoke, odour, smog or vapours in the outdoor atmosphere which is injurious to human, animal or plant life or which unreasonably interferes with the comfortable enjoyment of life and property.”

There are two types of air pollutants which cause air pollution :
(i) Primary air pollutants :
Natural pollutants—Bacteria, pollens, products of volcanic eruptions.
Aerosols—Dust, smoke, mist, fog.
Gases—CO2, CO, SOx, NOx, hydrocarbons etc.

(ii) Secondary air pollutants :
eg. Smog—mixture of smoke, fog, air and other chemicals.
Prevention of air pollution :
The following methods are used for the prevention of air pollution :

  • Zoning.
  • Control of air pollution by sources.
  • Control of air pollution by using devices.
  • Control of air pollution by means of stacks.
  • Control of air pollution by growing vegetation.

RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry

Question 26.
What is Green Chemistry and what are its contributions in prevention of pollution?
Answer:
Green Chemistry: Green Chemistry is an area of Chemistry and Chemical Engineering focussed on the designing of products and processes that minimize the use and generation of hazardous substances. It is also known as Sustainable Chemistry.

Green Chemistry was proposed in 1990 to control environmental pollution. According to Green Chemistry, the use of such chemicals, reactants, solvents etc. should be encouraged which are not hazardous to human beings.

Contributions of Green Chemistry in Prevention of pollution : Green Chemistry is the Philosophy of Chemistry whose aim is to modify present practices in order to prevent problems in the future. It plays an important role in prevention of pollution. Some strategies of Green Chemistry which can be adopted are :

  • Optimisation of balance of global mass in order to minimize waste.
  • Minimisation of energy consumption, eg. designing process at ambient temperature and pressure.
  • Wherever possible replacement of old compounds with others which maintain their functional efficiency while minimizing their toxic impact on the environment and human health.
  • Some aqueous and non-aqueous solvents should be developed which are not harmful for human being and also do not cause environmental pollution.
  • Use of biodiesel and hydrogen in vehicles should be encourged.
  • To release the minimum amount of wastes.

Green chemistry is a new field but it has significant achievement in control of pollution. By using green chemistry we can prepare a prototype of any chemical reaction and can study the used chemical and properties of products.

When a chemical reaction is carried out in ultraviolet light, Sound wave and microwave then use get positive output. Now a days enzymes is used as catalyst in the manufacturing of antibiotics. Some organic solvent is formed by using green chemistry that are harmful to human health nor the cause of pollution.

SO2 can be reduced to sulphur by using green chemistry, so that air pollution can be reduced.
RBSE Solutions for Class 11 Chemistry Chapter 14 Environmental Chemistry 4
SO2 gas can be absorbed by using limestone
2CaCO3 + 2SO2 + O2 ➝ 2CaSO4 + 2CO2
In green chemistry zeolite based detergent is used which reduces polution. Now CO2 is used for packing of foam sheet in place of chlorofluro carbon.

Similarly research are carried out to use helium in place of petrol and disel to stop of pollution caused by moter vehicle.

Various method to produce agriculture chemicals is discovered in which we can use poisonous material like cynide, formaldehyde etc.

RBSE Solutions for Class 11 Chemistry