What is the full form of $COD$?

The statements that are $TRUE$:
$A$. Methane leads to both global warming and photochemical smog.
$B$. Methane is generated from paddy fields.
$C$. Methane is a stronger global warming gas than $CO_2$.
$D$. Methane is a part of reducing smog.
Choose the most appropriate answer from the options given below:

The contribution of laughing gas $(N_2O)$ to global warming is ......%.

Match the items in List-$I$ with the items in List-$II$ and select the correct answer from the given options:

List-$I$	List-$II$
$A$. Bleaching of paper	$I$. $CF_2Cl_2$
$B$. Eye irritant	$II$. $H_2O_2$
$C$. Freons	$III$. $Na_2AsO_3$
$D$. Herbicide	$IV$. $PAN$
	$V$. $CO_2$

Which of the following chemicals is not involved in photochemical smog formation?

Which of the following statements is $NOT$ true about acid rain?