(i) Geeta shows awareness about the environment and she very well understands her moral duties towards it.
(ii) Various irrepairable electronic goods like irrepairable computers are not in use are known as electronic waste (e-waste). For controlling this problem the e-waste should be carefully handled. They should be safely burried in landfills or incinerated, or recycled for future use.

(a) Delhi Government shifted to CNG (Compressed Natural Gas) because:
(i) It burns more efficiently, unlike petrol or diesel, in automobiles and very little of it is left unburnt.
(ii) CNG is cheaper than petrol and diesel
(iii) It cannot be siphoned off by thieves.
(iv) It cannot be adulterated like petrol or diesel.
(b) Biochemical oxygen demand (BOD) refers to the amount of the oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria., As the BOD value is higher at A, therefore, the amount of dissolved oxygen is lower in that place. Excessive growth of algae, plants and animals in water bodies due to the nutrient enrichment, particularly with nitrogen and phosphorus, and discharge of domestic sewage into a river result in the rise of.BOD. However, as the organic matter is decomposed, there is a gradual rise in the amount of dissolved oxygen downstream.

(a) Chlorofluorocarbons (CFCs) are added to the stratosphere, which have a permanent and continuing effect on ozone levels. Although ozone depletion is occurring widely in the stratosphere,the depletion is particulary marked over the Antarctic region. This has resulted in the formation of a large area of the ruined ozone layer, commonly called as the ozone hole. Ozone depletion causes UV radiations to increase about 10%, which results in various diseases including skin cancer and eye disease.
(b) DDT is insoluble in water but soluble in fats. Due to low efficient transfer of energy from one trophic level to other, herbivores eat more DDTpolluted vegetables. Similarly, carnivores eat many herbivores. Apredator stores, much quantity ofDDT with its prey continuously. This process continues for several years by which more concentration of DDT accumulates in top carnivores. DDT interferes the eggshell formation in many birds. It causes premature breaking of eggshells, eventually causing decline in bird populations.

(iii) No, Alok was a brave and courteous boy. He expressed his love for animals, commitment towards natural resources and their conservation.

Effects of man-made chemicals on ozone layer.

Air pollution. Air pollution refers to the release into the atmosphere of materials that are harmful to man, other animals, plants and buildings or other objects.
Preventive measures for air pollution
To prevent and control air pollution two types of measures can be adopted.
1. Instead of releasing poisonous gases containing various pollutants into the atmosphere they could be destroyed or used by some other measures.
2. Converting harmful pollutants to harmless products and then releasing them into the atmosphere.

Characteristics of a modern landfill site includes.
(i) Methods to contain leachate such as lining clay or plastic liners.
(ii) Compaction and covering of the waste to prevent it from being to check seepage of chemicals which can pollute underground water resources blown by wind.
(iii) Installation of a landfill gas extraction system to extract the gas for use in generation of power.
The use of modern landfill sites must be promoted due to the following reasons
1. They stimulate the waste prevention via recycling and recovery of waste.
2. They create a uniform cost for the disposal of waste which consequently will prevent the unnecessary transport of waste.
3. They prevent or reduce the negative effects on the environment, as well as the risks to human health arising from the landfilling of the waste.

Defunct Ships
1. They constitute a kind of solid waste and require proper disposal. Such ships are broken down in developing countries like India, Pakistan, Bangladesh etc. where cheap labour force is available and they also use the scrap metal. The biggest ship-breaking yard is in Alang (Bhavnagar), Gujarat.
2. The defunct ships contain toxic substances like asbestos, polychlorinated biphenyls (PCBs), Tributylin (TBT), lead, mercury, etc.
3. The workers breaking the ships are not suitably protected and they are exposed to toxic chemicals.
4. The coastal area in the vicinity becomes polluted.
5. Asbestos is carcinogenic; it causes cancer and also an occupational lung disorder called asbestosis.
6. PCBsenter the food chain and cause biological magnification.
E-wastes
1. Irreparable computers and other electronic gadgets are the main source of e-wastes.
2. Incineration and burying in landfills are the two major ways of disposal of e-wastes.
3. E-wastes are recycled to recover metals like copper, iron, silicon, nickel and gold.
4. In developed countries, they are recycled in specifically built chambers, without involving labourers.
5. In developing countries, recycling involves human labourers.

Radioactive wastes
1. Radioactive waste is an extremely potent pollutant.
2. The radiation given by the nuclear waste causes mutations and hence is extremely damaging to living organisms.
3. At high doses, the nuclear radiation is lethal and at low doses, it causes cancer.
4. The storage of radioactive waste after sufficient pre-treatment is done in suitably shielded containers buried within the rocks, about 500 m deep below earth's surface.

(a) Ozone layer in the stratosphere acts as a shield to absorb the ultraviolet radiation from the sun, which is highly injurious to living organisms.
1. Chlorofluorocarbons (CFCs), from refrigerators and aerosol sprays, degrade the ozone layers.
2. The UV rays act on the CFCs and release CI atoms; which degrade ozone to molecular oxygen.
(b) In the absence of ozone, which absorbs the ultraviolet radiation, the UV rays reach the earth and cause the following ill-effects.
(i) UV-B damages DNA and causes mutation in living organisms.
(ii) It causes ageing of skin, damage to skin cells and various types of skin cancers.
(iii) A high dose of UV-B causes inflammation of cornea, called snow-blindness, cataract and even permanent damage to cornea.

FOAM: Friends of Arcata Marsh
1. It is a citizens group responsible for the upkeep and safeguarding of a project of integrated waste water treatment in the town of Arcata in the northern coast of California.
2. Collaborating with the biologists of Humboldt State University, the people of the town created an integrated waste water treatment process within a natural system.
The cleaning occurs in two stages:
(i) The conventional sedimentation, filtration and chlorination are done; after this, the dangerous pollutants like dissolved heavy metals remain.
(ii) The biologists developed a series of six connected marshes over 60 hectares of marshland; and seeded into them appropriate plants, algae, fungi and bacteria, which neutralise, absorb and assimilate the pollutants.
3. As water flows through the marshes, it gets purified naturally.
4. The marshes also constitute a sanctuary with a high level of biodiversity including fishes, birds and other animals which reside there now.