Which of the following ring compounds obeys Huckel's rule?

Which of the following statements are correct with respect to benzene?
$(i)$ It forms triozonide with $O_3$.
$(ii)$ It is non-planar.
$(iii)$ It forms only one monosubstituted product with $CH_3COCl$ in the presence of anhydrous $AlCl_3$.
$(iv)$ It forms hexachlorobenzene on heating with $Cl_2$ under photochemical conditions.

The starting material for the preparation of styrene is

Which of the following products cannot be obtained in the ozonolysis of $o$-xylene?

Among $P$,$Q$,$R$ and $S$,the aromatic compound$(s)$ is/are:

Which order is correct for the decreasing reactivity to ring monobromination of the following compounds: $C_6H_5CH_3$ $(I)$,$C_6H_5COOH$ $(II)$,$C_6H_6$ $(III)$,and $C_6H_5NO_2$ $(IV)$?