The electrophile used in the sulfonation of benzene is..........

Among the following compounds,the one that undergoes sulfonation most easily is .......

The major product $U$ in the following reactions is

In the conversion of $A$ to $B$,the electrophile involved is:

What products are formed when the following compound is treated with $Br_2$ in the presence of $FeBr_3$?

What is the ratio of glyoxal to pyrualdehyde obtained in the ozonolysis of $o-xylene$ as shown in the reaction below?
$o-Xylene$ $\xrightarrow[{(2) Zn}]{{(1) O_3}} CHO-CHO \text{ (Glyoxal)} + CH_3CO-COCH_3 \text{ (2,3-Butanedione)} + CH_3CO-CHO \text{ (Pyrualdehyde)}$