Bromination of isobutane is a two-step reaction and the reactions in the image correctly depict that.
What is the bromination of isobutane?
The bromination of isobutane involves two steps which are the radical initiation and hydrogen abstraction and the radical propagation and halogenation.
A bromine molecule breaks apart due to heat or UV light, forming two highly reactive bromine radicals. One of these radicals attacks the isobutane molecule, abstracting a hydrogen atom from one of the methyl groups.
Next, the tertiary butyl radical reacts with another bromine molecule, stealing a bromine atom and forming a brominated isobutane molecule (C(CH₃)₃Br) and another bromine radical.