Lead is considered as

What will happen in the future if the current rate of air pollution continues?

Consider the following reactions involving some atmospheric pollutants:
$NO + O_3 \rightarrow NO_2 + O_2$
$NO_2 \xrightarrow{h \nu} NO + O$
$O + O_2 \rightarrow O_3$
$4 NO_2 + O_2 + 2 H_2 O \longrightarrow 4 HNO_3$
$3 CH_4 + 2 O_3 \longrightarrow 3 H_2 C = O + 3 H_2 O$
Based on the above,the formation of formaldehyde from methane in the atmosphere will be controlled by:

State whether the following statements are true or false:
$(1)$ The concentration of oxygen in cold water is $100 \ ppm$.
$(2)$ If the concentration of dissolved oxygen in water is less than $6 \ ppm$,the growth of fish gets inhibited.

The depletion of the ozone layer in the stratosphere is responsible for which of the following?

The poisonous gas that is released during the combustion of petrol in a car engine is