Important Questions for Class 12 Chapter 16 - Environmental Issues

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Important questions based on NCERT syllabus for Chapter 16 - Environmental Issues:

Question-1: List all the wastes that you generate, at home,school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?

Solution: Plastic containers, paper, electronic goods, left over food, food package, disposable glasses, cup plates, polythenes, excreta, soap and detergent waste are the wastes that one can generate at home, school or during trips to other places. Yes, we can easily reduce waste through judicious use of material by changing our habits & life styles.
Out of these, polythene and plastic material are hard to dispose off as they are non- biodegradable and they can be recycled back.

Question-2: Why does ozone hole forms over Antarctica? How will enhanced ultraviolet radiation affect us?

Solution: A large amount of ODS (Ozone Depleting Sub-stances) like CFCs, N2O, halons, SO2, CH4, Cl-are released by advanced countries like USA, Japan, European countries. These are released in stratosphere, drift towards poles and reach there before the coming of winter. During winter (temp. 85°C) ice clouds are formed over Antarctica and no sunrise is received in polar areas. It catalyses release of Cl from CFCs. With the coming of spring season, Cl reacts with ozone in the presence of sunlight and converts 03 into 02 causing ozone depletion/thining of ozone shield in stratosphere called ozone hole. This hole disappears in summer due to free mixing of air ofAntarctica with therestofthe global air. Effect of Enhanced UV Radiation, (i) Snow blindness or inflammation of cornea (ii) Damage of skin cells and development of skin cancer, (iii) Damage to nucleic acids and proteins, (iv) Reduced immunity (v) Higher number of cataracts in humans.

Question-3: What measures, as an individual, would you take to reduce environmental pollution?

Solution: To reduce environmental pollution we should take following measures:
(i)Reducing use of CFC.
(ii)Disposing off waste safely.
(iii)Reducing use of polythene.
(iv)Not disposing off waste in water bodies.
(v)Making automobiles pollution free.
(iv)Prevention of noise pollution by using fire crackers/TV/musical instruments at permissible limits.
(vii)Tree plantation in school, around residence.