Environmental Chemistry Class 11 chemistry

 

Environmental Chemistry Class 11 chemistry 

What is troposphere?

The lowest region atmosphere in which the human beings along with other organisms live is called troposphere. It extends upto the height of  10 km from sea level. 

What is the role of ozone layer in the stratosphere?

The presence of ozone in the stratosphere prevents about 99.5% of the sun’s harmful ultraviolet (uv) radiations from reaching the earth’s surface and thereby protecting humans and other animals from its effect. 

Name some gaseous air pollutants. 

Gaseous air pollutants are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.

What are the diseases caused by sulphur dioxide?

Sulphur dioxide causes respiratory diseases eg. asthma, bronchitis, emphysema in human beings, sulphur dioxide causes irritation to the eyes, resulting in tears and redness. 

What includes stratospheric pollutants? Give examples. 

Depletion of ozone layer in stratospheres leading to reach harmful uv radiation on earth is the result of stratospheric pollution. The presence of chloro fluoro carbon compounds in the atmosphere is responsible for this depletion.

What are the harmful effects of oxides of nitrogen in atmosphere?

(i) High concentration of NO2 in atmosphere is harmful to plants resulting in leaf spotting, retardation of photosynthetic activity and also suppression the vegetation growth. 

(ii) Nitrogen dioxide (NO2) results in respiratory problems in human beings and leads to bronchitis. It causes acid rain. Produce photochemical smog. 

(iii) Oxides of nitrogen have harmful effects on the nylon, rayon and cotton yarns and also cause cracks in rubber.

(iv)They also react with react with ozone (O3) present in the atmosphere, and, their decrease the density of ozone. 

Why is carbon monoxide considered to be poisonous? 

Carbon monoxide binds to hemoglobin to form carboxyl – haemoglobin, which is about 300 times more stable than the oxygen – haemoglobin complex. In blood when the concentration of carboxyl hemoglobin is greatly reduced. This oxygen deficiency, results into headache, weak eyesight, nervousness and cardiovascular disorder. 

What are the ill-effects of hydrocarbons? 

Hydrocarbons are carcinogenic i. e; they cause cancer. They harm plants by causing ageing, breakdown of tissues and shedding of leaves flowers and trigs. 

List gases which are responsible for green house effect? 

Carbon dioxide, methane, water vapors, nitrous oxide, CFC’s and ozone are responsible for green house effect. 

What is the effect of CFC’s on ozone layer?

Chlorofluorocarbon (CFC’s) damage the ozone layer and creates holes in ozone layer. 

Give one main reason of ozone depletion?

The main reason of ozone depletion is the release of chlorofluoro compounds (CFC’s) in the atmosphere also known as Freon.

Which zone is called ozonosphere? 

Stratosphere zone is called ozonosphere

What is ‘greenhouse effect’? How does it affects the global climate? 

The warming of the earth or global warming due to re-emission of sun’s energy absorbed by the earth followed by its absorption by CO2 molecules and H2O vapours present in the atmosphere, near the earth’s surface and then its radiation back to the earth is called greenhouse effect. Greenhouse affects the climate. If the rate at which solar radiation are arriving the earth continues, then the entire global climate is going to change drastically. 

What is greenhouse effect?

Atmosphere traps the Sun’s heat near the Earth’s surface and keeps it warm. This is Greenhouse effect. 

Which disease is caused due to ozone layer depletion?

Ultraviolet rays reaching the earth passing through the ozone hole cause skin cancer.

What are the ill effects of ozone hole? 

Consequences of Ozone hole: The ultraviolet rays entering into the earth through ozone hole leads to (i) Increase cases of skin cancer 

(ii) It affects plants, chlorophyll, proteins and causes harmful mutation in them. 

(iii) Upset the heat balance of the earth 

(iv) Ecological imbalance, which would adversely affect man and animals.  

What is smog?

When smoke with fog, it is called smog. 

The London smog is caused in which season and time of the day?

The London smog is caused during summer season and in the afternoon part of the day when it is very hot. 

What is PAN? 

PAN is Peroxy acetyl nitrate.

What is the composition of photochemical smog? 

Photochemical smog is formed as a result of photochemical reaction (i. e; in the presence of sunlight) between oxides of nitrogen and hydrocarbons. 

When does rain water become acid rain? 

When pH of rain water becomes as low as 2 to 3.5. It forms acid rain. 

How can photochemical smog be controlled?

If we control the primary precursors of photochemical smog such as NO2 and hydrocarbons, the secondary precursors such as ozone and PAN, the photochemical smog will automatically be reduced. Usually catalytic converters are used in the automobiles which prevent the release of nitrogen oxide and hydrocarbon to the atmosphere. Certain plants eg. Pines, Juniparus, Quercus, Pyrus and Vitis can metabolise nitrogen oxide and their plantation could help in this matter. 

What is BOD?

BOD stands for Biochemical Oxygen Demand. 

What does the amount of BOD signify?

The amount of BOD in water is a measure of the amount of organic material in the water, in terms of how much oxygen will be required to break it down biologically. Clean water would have BOD value of less than 5 ppm whereas highly polluted water would have a BOD value of 17 ppm or more. 

Define green chemistry.

The branch of chemistry that emphasizes on the processes and products that reduce or eliminate the use and generation of toxic / hazardous substances is called green chemistry. 

What are pesticides?

Pesticides are those chemicals which are used to destroy pests, rats, parasites and fungi. 

What should be the pH of drinking water? 

 The pH of drinking water should be between 5.5 and 9.5.


What is the desirable concentration of fluoride ion (F- ) in drinking water?
1ppm or 1 mg dm-3 is desirable concentration of F- ions in drinking water.


What is pneumoconiosis? 

The smaller particulate pollutants are more likely to penetrate into the lungs. These five particles are carcinogens Inhalation of small particles irritates the lung and exposure to such particles for long period of time causes fibrosis of the lung lining. These type of disease is termed as pneumoconiosis.


Discuss the water pollution caused by industrial water?
The compounds of lead, mercury, Cd, Ni, Co, Zn etc which are the products of chemical reactions, carried in the industrial units, pollute water to a large extent and are responsible for many disease. Mercury leads to minimarts disease, lead poisoning leads to many deformities. In addition, these substances adds to the soil and harmfully affect the plant growth and the whole soil biotic system. Both ground water and water bodies are polluted due to chemical reactions known as leaching.


What is an insecticide?
Insecticides are used to control insects and curve disease (for eg. malaria and yellow fever) and protect crops. Eg. DDT.