Read the passage carefully and answer the following question in your own words :
The water of river Yamuna in Delhi has become useless. The water of this river is most polluted and has received 'E' grade in terms of quantity. This is the lowest grade which indicates the severity of pollution in the river water. Some fifty years ago the water of the Yamuna was clear and clean. Many water plants such as weeds, algae and shrubs grew in its water or along the bank of the river. These plants were the main source of food for aquatic creatures. A number of waterbirds could be seen along the river. With the onset of winter thousands of migratory birds would come here to feed in the Yamuna water. Sadly these water species and birds have vanished of death. What one finds now are red worms called chironomids which live in the most unhygienic and polluted water.
(i) How can you say that the water of river Yamuna is useless?
(ii) What kind of plants is narrator talking about?
(iii) Why the migrate birds came near to river Yamuna?
(iv) What kind of worms are found in the river Yamuna?
