Is not a single replacement
Further explanation
A single replacement reaction is a chemical reaction in which one element replaces the other elements of a compound to produce new elements and compounds
Reactions
A+BC--> AC+B
Metal halogens can force metal halide ions in the order F> Cl> Br> I
Oxidation : F₂> Cl₂> Br₂> I₂
Reaction
NaBr+I₂ -> NaI+Br₂
Then the reaction will not occur because I₂ cannot oxidize Br, or the reaction is said to be non-spontaneous