Question

Arrange the following compounds in the increasing order of homolytic $(C-C)$ bond dissociation energy.

I. Propane
II. Ethane
III. 2, 2-Dimethyl propane
IV. 2-Methyl propane

• A. (III) < (IV) < (II) < (I)
• B. (II) < (I) < (IV) < (III)
• C. (III) < (IV) < (I) < (II)
• D. (I) < (III) < (II) < (IV)

Answer 1

The correct option is B (II) < (I) < (IV) < (III)

The increasing order of homolytic (CC) bond dissociation energy is $Ethane\left(II\right)<Propane\left(I\right)<-Methylpropane\left(IV\right)<2,2-Dimethylpropane\left(III\right)$.
Alkyl groups show +I effect. Thus, they are electron donating groups.
With increase in the number of alkyl groups, the homolytic (CC) bond dissociation energy increases as the C-C bond becomes stronger.