Which of the following C-H bond has the lowest bond dissociation energy

Options

A. Primary `(1^@)` C- H bond
B. Secondary `(2^(@))` C -H bond
C. Tertiary `(3^(@))` C-H bond
D. All of these

Answer

C

Explanation

Nature always try to achieve least potential energy for stability. Any organic reaction which makes the product less stable is not favourable.
If the C-H bonds are cleaved homolytically in all cases, the resulting stability of the free radicals will tell us about the feasibility of the reaction
The primary free radical is the most unstable and to bring about its C-H bond breaking would mean increasing its energy comparatively. Hence its bond energy is the most and so it is the stronger bond of the three.
Tertiary free radicals is the most stable .
The same explanation can be used to draw out their comparative strength of the C-H bonds