What is the full form of $CNG$?

The dental disease characterized by mottling of teeth due to the presence of a specific chemical in drinking water is caused by which of the following elements?

$A$ scrubber in the exhaust of a chemical industrial plant removes

Find out what the terms 'algal bloom' and 'red-tides' signify.

Carbon monoxide causes:
$I.$ Giddiness
$II.$ Headache
$III.$ Decreased vision
$IV.$ Cardiovascular malfunction
$V.$ Asphyxia
Which of the statements given above are correct?

Concentration of $DDT$ in zooplankton is