Question

What is bond dissociation enthalpy?

Answer 1

Dear student!

Bond dissociation enthalpy is the energy required to break a bond and as we move down a group the bond length increases.

Shorter is the bond higher will be the strength. So, down the group, the bond length increases and so the bond strength decreases and thus it will require very few energy to break the bond and so the bond dissociation enthalpy decreases down the group and increases along a period.