$\text { O=O }\quad\quad\quad\quad\quad\quad 498$

$H - H \quad\quad\quad\quad\quad\quad 436$

$H - H$ bond energy is very high, comparable to the bond dissociation energy of $O _2$, because $H - H$ bond is formed by is orbital of $H$ atoms.

$(B)\text { Molecules } \text { Bond energy. }( KJ / mol )$

$N \equiv N \quad\quad\quad\quad\quad\quad 945$

$\overline{ C } \equiv \stackrel{+}{ O } \quad\quad\quad\quad\quad\quad1072$

$N \equiv N$ bond is comparably weaker than $C = O$ bond due to presence of lone pair - lone pair repulsion resided on $N$ atom.

$C)$ Molecules Bond energy. $( KJ / mol )$

$F - F \quad\quad\quad\quad\quad\quad 156$

$I - I \quad\quad\quad\quad\quad\quad 151$

The atomic radius of $F$ atom is so small that the electrostatic repulsion between nuclei is significant and non-bonding electrons of $F$ atoms repel each other. As a result $F-F$ bond energy is almost identical with bond energy of $I- I$ which is weaker due to formation of bond by $sp$ orbital of $I$ atom.

$D)$ bond energy of $O _2(498\, KJ / mol )$ is higher than that of $Cl _2(243 \,KJ / mol )$ because of double and single bond character of $O _2$ and $Cl _2$ respectively. Correct pair will be $(C)$ $F _2$ and $I _2$.