Question

Which of the following bonds has the highest bond energy?
A.$S - S$
B.$O - O$
C.$Se - Se$
D.$Te - Te$

Answer 1

We need to know that the bond energy is also known as mean bond enthalpy. And the bond energy is used to measure the bond strength present in a chemical bond. If the average bond energy is more in an electron pair bond present in a molecule, the molecule will be more stable. And the bond energy can be measured by using the required amount of heat for the breakage of one mole present in a molecule to their individual atoms.

Complete answer:
Among the following compounds,$S - S$ has the highest bond energy and it has the highest bond strength and it is equal to $49kcal/mol$. Because, size is more and the lone pair of electrons of sulphur atoms does not repel each other. Therefore, it has higher bond energy. Hence, option (A) is correct.
The size of oxygen is less than sulphur and the lone pairs present in the oxygen repel each other and the bond strength will become weak. Hence, option (B) is correct.
The bond energy decreases when moving down the group due to increasing the size of the atom and radius. Thus, it requires very less amount of energy to break that bond. Hence, option (C) is incorrect.
Among the given compounds, the bond length of $Te - Te$ is more and it requires less amount of bond energy. Hence, the option (D) is incorrect.

Note:
We must have to know that the bond energy is the energy needed to break the covalent bond which is present in between two atoms. If the bond energy is high, which means, the bond is stronger and it needs a huge amount of energy to break that bond. And that compound will be more stable and it should be less reactive. The bond energy depends on the size of the compound and bond length.