The degradation of natural resources can occur not only by the effects of pollutants but also by improper practices of resource utilisation. For example, the formation of fertile top soil takes centuries, but it is removed very easily (soil erosion) due to certain human activities.
(a) Write any four such human activities that lead to soil erosion.
(b) Mention two such problems that have come in the wake of Green Revolution.

Ozone gas is continuously formed by the action of UV rays on molecular oxygen and· also degraded into molecular oxygen. There should be a balance between the formation and degradation of ozone in the stratosphere.
(a) What is meant by ozone hole?
(b) Mention the unit to measure the thickness of ozone. 
(c) When is the ozone hole formed each year?

Greenhouse effect is a naturally occurring phenomenon that is responsible for heating earth's surface and atmosphere. Earth's surface emits heat in the form of infrared radiation, but most of it is absorbed by certain gases, called greenhouse gases, leading to global warming.
(a) Name two gases that contribute the most to global warming and mention their relative contribution towards this.
(b) What would have been the temperature of earth without greenhouse effect?
(c) What is the mean temperature ofthe earth now?

With the revolution of information technology, it has become an integral part of everyone's life, both in rural and urban India.
(a) Write howe-wastes are generated?
(b) How have the developed countries exploited the developing countries with respect to e-waste management?
(c) Mention the correct solution for the treatment of e-wastes.

Observe the diagram of the catalytic converter given above and answer the following questions.
(a) Name the best fuel for vehicles fitted with catalytic converter. Justify your answer.
(b) What happens to nitric oxide and carbon monoxide in the automobile exhaust, when passed through the catalytic converter?
(c) Name any two metals used as catalyst in the catalytic converter.