People living in West Bengal suffer from black foot disease. This is caused by the contamination of groundwater with which of the following?

Catalytic converters,which have expensive metals as catalysts,are fitted into automobiles for reducing emission of poisonous gases. Which of the following is $NOT$ used in them?

$A$ location with luxuriant growth of lichens on the trees indicates that the

What is the density of heavy metals?

Fly-ash is a/an :

The term used for the accumulation of non-degradable pollutants in higher trophic levels is: