India is hugely dependent on thermal and hydro power plants to meet its power requirements. Both these plants have adverse environmental impacts. Thermal power plants emit large quantities of carbon dioxide - a greenhouse gas and also produces fly ash which can pollute water bodies, land and other components of the environment. Hydro-power plants innundate the forests and interfere with the natural flow of water in catchment areas and the river basins.
(a) Which are the two types of power plants on which India depends upon for its power requirements?
(b) Elaborate the impact of these power plants on India's environment.

Economic development which aimed at increasing the production of goods and services to meet the needs of a rising population, puts greater pressure on the environment. In the initial stages of development, the demand for environmental resources was less than that of supply. Now the world today is faced with increased demand for environmental resources but their supply is limited, due to overuse and misuse. Sustainable development aims at promoting the kind of development that minimises environmental problems and meets the needs of the present generation without compromising the ability of the future generation to meet their own needs.
(a) How does economic development put greater pressure on environment?
(b) Give the aim of sustainable development.