Question

jolene wants to experiment with sugar cubes. which of the following causes a sugar cube to only change physically, not chemically? a) burning the sugar cube with a match b) crushing the sugar cube and dissolving it in water c) dehydrating the sugar cube with sulfuric acid d) chewing the sugar cube and digesting it a physical change occurs when... a) both the appearance of a substance and its identity change. b) the appearance of a substance changes but its identity does not. c) the identity of a substance changes but its appearance does not. d) neither the appearance of a substance nor its identity changes.

Explanation:

For the first question, burning sugar is a combustion reaction (chemical change), dehydrating with sulfuric - acid is a chemical reaction, and digestion is a chemical process in the body. Crushing and dissolving sugar in water only changes its physical form (from solid cube to dissolved particles), not its chemical identity. For the second question, by definition, a physical change is when the appearance of a substance changes but its chemical identity remains the same.

Answer:

1. B. crushing the sugar cube and dissolving it in water
2. B. the appearance of a substance changes but its identity does not.