Question

Bond energy of a molecule is:
(a) always positive
(b) either positive or negative
(c) always negative
(d) dependent on the physical state of the system

Answer 1

Hint: The energy supplied to break the bond constitutes its bond energy and negative value of energy indicates that the energy is released by the system and positive value of energy indicates that the energy is supplied to the system. Now answer the statement.

Complete answer:
First of all, let’s discuss what bond energy is. By the bond energy, we simply mean the energy which is required to break the bond. It is also known as the bond enthalpy.
The energy required to break the bond depends upon the bond strength. Stronger the bond strength in the molecule , more is the energy which is required by the molecule to break the bond and hence the value of bond energy will be more.
On the other hand, if the bond strength is weaker in the molecule then in that case lesser energy is required to break the bond and hence the value of bond energy will be less.
Since, energy has to be supplied to break the bond , so the bond energy for a molecule is always positive.

Hence, option (a) is correct.

Note: Through bond energy we can determine the bond strength of any compound. Greater the value of energy means greater is the bond strength and on the contrary lower value of the energy, indicates lower is the bond strength.