Answer
The magnitude of the impulse exerted on each ball is the same.
Work Step by Step
During the collision, the rubber ball exerts a force on the steel ball. According to Newton's third law, the steel ball exerts an equal and opposite force on the rubber ball. Since the magnitude of the force on each ball is equal and the time of the collision is the same for both balls, the magnitude of the impulse exerted on each ball is the same.