Question

Arrange the following bonds according to their average bond energies in descending order :
$C-Cl,C-Br,C-F,C-I$

(JEE MAIN 2020)

• A. $C-F>C-Cl>C-Br>C-I$
• B. $C-I>C-Br>C-Cl>C-F$
• C. $C-Cl>C-Br>C-I>C-F$
• D. $C-Br>C-I>C-Cl>C-F$

Answer 1

The correct option is A $C-F>C-Cl>C-Br>C-I$

Size of halogen atoms increase down the group.
Thus, the bond length of $C-X$ increase down the group and the bond strength decrease down the group.
Hence, average bond energy decrease down the group.
$C-F>C-Cl>C-Br>C-I$
Hence, option (b) is correct.