Jennifer mixes substances during a lab experiment. She observes the four effects listed below. Which of these effects indicated that a chemical reaction has taken place? a. A clear, lemon-scented liquid continues to smell like lemon when it is mixed with water. b. A piece of shiny metal begins to bubble when placed in a clear liquid. c. A pink powdered substance turns water pink when they are mixed together. d. A white solid disappears when mixed with water.