Answer:
Single displacement reaction
Step-by-step explanation:
When Potassium Iodide reacts with chlorine, the following reaction occurs
2KI + Cl₂ ⇒ 2KCl + I₂
From the reaction above, it can be deduced that chlorine replaces iodine in potassium iodide to form potassium chloride. This type of reaction is called a single displacement reaction. And it usually occurs when a more reactive element displaces a less reactive element from it's compound.
Chlorine is more reactive than iodine and as such can displace iodine from a solution (just as it is in the equation above).
NOTE: A single displacement reaction is a reaction in which an element (just one) replaces another element in a compound during the course of a reaction.