As part of a science experiment, Jose did a test for starch on a slice of apple and a slice of potato. The yellow-orange iodine solution stayed the same color when it was put on the apple, but it became black on the potato.

Question

Why did the iodine solution change color on the potato?
A.
The iodine mixed with the colors of the potato so it looked black.
B.
The iodine evaporated into a gas.
C.
The iodine burned the potato and turned it to ash.
D.
The iodine reacted with the potato to form a new substance.

Answer 1

The correct answer is:

D. The iodine reacted with the potato to form a new substance.

The iodine solution changes color to black when it comes into contact with starch, which is present in the potato. This reaction indicates the presence of starch in the potato. The apple, on the other hand, contains little to no starch, which is why the iodine solution did not change color when applied to it.