Answer:
The factor is 2
Explanation:
Van't Hoff factor is defined as the ratio between the species of a solute before the addition to the solvent and particles produced when the substance is dissolved. It is used, principally, in colligative properties.
Before solution, potassium bromide, KBr, has just one specie, that is, KBr. When KBr is dissolved (As a salt):
KBr(aq) → K⁺(aq) + Br⁻(aq)
There are produced two species, K⁺ and Br⁻. By definition of Van't Hoff factor, for this salt, the factor is 2.