Leukaemia is caused by

Which metal is the most harmful pollutant emitted by automobiles?

Catalytic converters are fitted into automobiles to reduce the emission of poisonous gases. These converters use expensive metals as catalysts,which are:

In Minamata Bay,Japan,which of the following animals remained free from Minamata disease?

$DDT$ is a/an:

Exposure to a noise level of $............$ or more for a short period can damage the eardrums,leading to permanent hearing impairment. (in $,dB$)