Methemoglobinemia is caused by the presence of $X$ in drinking water. $X$ is

Mention two side effects caused by acid rain.

$A$ water sample is considered the cleanest based on which of the following $BOD$ values (in $ppm$)?

Arrange the following hydrocarbon fuels in increasing order of their polluting strength: $LPG$,$CNG$,and Kerosene.

Given below are two statements :
Statement $I$ : If $BOD$ is $4\,ppm$ and dissolved oxygen is $8\,ppm$,then it is a good quality water.
Statement $II$ : If the concentration of zinc and nitrate salts are $5\,ppm$ each,then it can be a good quality water.
In the light of the above statements,choose the most appropriate answer from the options given below :

What efforts are being made by the government to save the Taj Mahal?