Chlorine atoms act as catalysts in the depletion of the ozone layer in the Earth's atmosphere. These chlorine atoms originate from which of the following?

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 is harmful to calcium-containing structures and is responsible for causing cough and throat irritation in humans?

Indiscriminate use of $DDT$ is undesirable because

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

Smog is primarily caused by the presence of which of the following?