Green chemistry means such reactions which

Formation of photochemical smog involves the following reactions in which $A$,$B$,and $C$ are respectively:
$(i)$ $NO_2 \stackrel{h\nu}{\longrightarrow} A + B$
$(ii)$ $B + O_2 \rightarrow C$
$(iii)$ $A + C \rightarrow NO_2 + O_2$
Choose the correct answer from the options given below:

The chlorine free radical reacts with ozone to form a ..... free radical.

Reducing smog is a mixture of

Chlorine gas reacts with the aromatic ring of lignin to form which of the following substances?

The presence of soluble fluoride ion up to $1 \ ppm$ concentration in drinking water is: