Answer:
During a chemical change, the composition of matter always changes. Four possible clues to chemical change include a transfer of energy, a change in color, the production of a gas, or the formation of a precipitate.
Explanation:
You are testing for the presence of starch: Iodine dissolved in an aqueous solution of potassium iodide - reacts with starch producing a deep blue-black color. This reaction is the result of the formation of polyiodide chains from the reaction of starch and iodine.
I may be wrong but maybe oil