Which of the following statements is not true about classical smog?

Among the following, the one which is not a "green house gas" is:

Match the following metals in drinking water with their maximum prescribed concentration in $ppm$:

List-$I$ (Metal)	List-$II$ (Concentration in $ppm$)
$A$. $Mn$	$I$. $0.05$
$B$. $Zn$	$II$. $5.0$
$C$. $Cd$	$III$. $0.005$
$D$. $Cu$	$IV$. $3.0$

Which of the following statements are correct?
a) $F^{-}$ ion concentration above $2 \ ppm$ causes brown mottling of teeth
b) The maximum limit of nitrate in drinking water is $400 \ ppm$
c) Depletion of ozone layer leads to cataract and skin cancer
d) The irritant red haze in the traffic is due to oxides of sulphur

The compound that is $NOT$ a common component of photochemical smog is

Which of the following statements are correct?
$A$. Ocean is a sink for $CO_2$.
$B$. Greenhouse effect causes lowering of the temperature of the earth's surface.
$C$. To control $CO$ emission by automobiles,usually catalytic converters are fitted into exhaust pipes.
$D$. $H_2SO_4$,herbicides,and insecticides form mist.