Which energy is used in wind mills ?

Which type of water is used for flushing toilets after recycling ?

Name the fungi which is used to treat polluted areas where there is high levels of nitrogen compounds ?

Which of the following changes occur in pond water during summer?

The energy derived directly from the sun is called as

Which one is an example for water - based diseases ?

Which one is an example for water borne disease?

_______ are absent in areas with water scarcity. 

Name the equipment used to evaluate the energy efficiency of house?

Study of physical, chemical and biological aspects of fresh water is called