In $OF _{2}$ repulsion between lone pairs is greater than that between bond pair since electrons are away from $O$ and nearer to $F$. In $Cl _{2} O$, bonding electrons are nearer to $O$ than to $Cl$, so the bond angle is greater than $109^{\circ} 28' .$ In $Br _{2} O$, the bonding electrons are more closer to oxygen than in $Cl _{2} O$, so the bond angle is largest $\left(116^{\circ}\right)$.
