After looking at the table I believe the answer is 5. phenolphthalein, color change at pH 8-10. Phenolphthalein is an organic compound used as an acid-base indicator. It is colorless in acid solutions and turns pink to red as the solution becomes alkaline. The compound is also medically used as a cathartic.
Atoms must gain or lose electrons in order to become ions if they are to form ionic bonds.
Earth's shape & the tilt of its axis causes the Sun's rays to strike different parts of Earth's surface. I hope this helped :)
