Which among the following pairs consists only of herbicides?

Methemoglobinemia ('blue baby' syndrome) disease is associated with

What are biodegradable and non-biodegradable pollutants?

Identify the correct statements from the following:
$a$) $BOD$ value of clean water is less than $5 \ ppm$
$b$) Oxidation of ethene in the presence of $Pd^{2+}$ catalyst in aqueous medium gives acetic acid
$c$) Photochemical smog causes damage to plant life
$d$) Reducing smog is a mixture of smoke,fog and $SO_2$

Methyl mercaptans are generated as waste from which industry?

Which among the following is not a greenhouse gas?