The image shows what happens when an antacid tablet is placed in water. A glass of water is shown with a tablet beside it. An arrow points to a second glass, where the tablet can be seen at the bottom of the glass with bubbles rising from the tablet. The process shown in the image can best be described as a rapid chemical reaction where gas is released. Slow chemical reaction where light is being given off. Slow chemical reaction where the liquid changes color. Rapid chemical reaction where heat is suddenly released.