Define a) Pollution b) Green house effect  c) Acid rain  d) Potable water

Pollution is the introduction into the air, water or ground of toxic substances that are damaging to human health and ecosystems.The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere trap energy from the sun.The term 'acid rain' refers to the acidification of rain associated with the combustion of fossil fuel: coal, oil and natural gasThe water that is suitable for drinking is called as potable water.