Methemoglobinemia is due to

Give two names of herbicides.

Soil containing both $Al$ and $Fe$ is called

Which of the following is not a greenhouse gas?

Given below are two statements.
Statement $I:$ In polluted water,values of both dissolved oxygen and $BOD$ are very low.
Statement $II:$ Eutrophication results in a decrease in the amount of dissolved oxygen.
In the light of the above statements,choose the most appropriate answer from the options given below.

The $Taj \ Mahal$ is being slowly disfigured and discoloured. This is primarily due to