What should happen when iki solution contacts something that does not contain starch?

IKI stands for Iodine-potassium iodide, it is a chemical that is used in the laboratory to test for starch. When IKI comes in contact with starch solution, it will turn to dark purple colour in the presence of starch. When starch is absent in a substance, the addition of IKI to that substance will not produce any change in colour.

The seafloor is only 180 million years old due to the process of subduction. The floor of the sea's tends to get colder and denser with the passage of time. At a certain time, the seafloor becomes so dense that it sinks in the upper mantle. The Earth's crust cannot undergo this process and hence has oldest rocks. We can say that the seafloor is less than 180 million years old because it is typically recycled back into the mantle of the Earth.