Which among the following has the highest concentration of $PAN$?

Which of the following statements about photochemical smog is wrong?

Green chemistry means such reactions which

State whether the following statements are true or false:
$(1)$ Severe respiratory diseases in children are caused by $NO_2$ gas.
$(2)$ Carbon monoxide binds with hemoglobin in the blood to form a carboxyhemoglobin complex.
$(3)$ The carboxyhemoglobin complex is $100$ times more stable than the oxygen-hemoglobin complex.
$(4)$ The $pH$ of rainwater is around $5.6$.

Which of the following is the correct order of greenhouse gases based on their $GWP$ (Global Warming Potential)?

The pair of gases responsible for acid rain are