Answer:
Bromine + Potassium iodide ➨potassium bromide + iodine
a)you would expect to see a brown solution and a black solid from the iodide
b)the reaction occurs because bromine displaces iodine as it's more reactive and has a higher oxidising power. Bromine is more reactive because it has a smaller atomic radius or less shells than iodine, so the outer electrons are closer to the nucleus. This makes it easier to gain an electron due to the stronger forces of attraction between the nucleus and outermost electrons compared to having more shells which is harder to gain.