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.
Answer:
Yersinia pestis is the causative agent of plague
Explanation:
Rodents, such as rats, carry the disease. It is spread by their fleas.
The most common source of contamination with E.coli is by eating contaminated food like meat and eggs.
