Question

Among the $C - X$ bond, (where $X = Cl,Br,I$) the correct bond energy order is
A.$C - Cl > C - Br > C - I$
B.$C - I > C - Cl > C - Br$
C.$C - Br > C - Cl > C - I$
D.$C - I > C - Br > C - Cl$

Answer 1

We also know that the bond energy is the amount of energy needed to split a mole of molecules and it forms its corresponding atoms. And it is equal to the amount of strength of the chemical bond. The bond energy mainly depends on the number of bonds present between the atoms. If the bond energy is more, then the bond length will become smaller and the molecule will be more stable.

Complete answer:
We have to remember that the bond energy is directly proportional to bond strength and difference in electronegativity. Chlorine is more electronegative than bromine and iodine and the order, $Cl > Br > I$. More electronegative atoms have more bond energy. Therefore, the bond energy of $C - Cl$ bond is stronger than $C - Br$ bond and $C - I$ bond and the order is,
$C - Cl > C - Br > C - I$
Hence, option (A) is correct.
The bond energy of $C - I$ is lesser than $C - Br$ and $C - Cl$ bond. Because, iodine is less electronegative than chlorine and bromine atoms. Hence, the option (B) is incorrect.
The bromine atom is less electronegative than chlorine atom. Hence, the option (C) is incorrect.
The bond strength and electronegativity of iodine is less than bromine and chlorine atoms. Hence, the option (D) is incorrect.

Note: We have to know that among the given halogen atoms, chlorine is more electronegative than bromine and iodine. The bond energy depends on electronegativity and bond strength. The bond energy is directly proportional to electronegativity and bond strength. Which means, when the bond strength increases, it requires more energy to break that bond. Hence, the bond energy increases. Hence, the correct order of bond energy order is, $C - Cl > C - Br > C - I$.