The bond dissociation energy is highest for

Which gas has been used since ancient times to remove lignin from wood?

Which substance is used as a gaseous insulator in high-voltage generators?

Compound $A$ and $B$ respectively are :-
$Cl_2 + 2NaOH (cold \& dil.) \rightarrow A + NaCl + H_2O$
$3Cl_2 + 6NaOH (hot \& conc.) \rightarrow B + 5NaCl + 3H_2O$

Chlorine gas reacts with red hot calcium oxide to give

On heating $KClO_3$,we get