In the upper atmosphere,ozone is formed by the action of which of the following?

Which of the given statements are correct, when carboxyhaemoglobin reaches $3-4 \%$ in blood?
$(I)$ Leads to headache
$(II)$ Results in cardiovascular problems
$(III)$ Increases the body temperature
$(IV)$ Leads to diarrhoea

Explain why sometimes foaming is seen in river water near the place where sewage water is poured after treatment?

Match List-$I$ with List-$II$

List-$I$ Industry	List-$II$ Waste Generated
$A$. Steel plants	$I$. Gypsum
$B$. Thermal power plants	$II$. Fly ash
$C$. Fertilizer industries	$III$. Slag
$D$. Paper mills	$IV$. Bio-degradable Wastes

Choose the correct answer from the options given below:

The gaseous envelope around the earth is known as the atmosphere. The lowest layer of this extends up to $10 \ km$ from sea level; this layer is $.......$

Dissolved oxygen is essential for aquatic life. What are the reasons responsible for the depletion of dissolved oxygen in water?