Which of the following would cause only a chemical change with a sugar cube

Which would cause only a chemical change in a sugar cube is heating the sugar cube with acid.

Explanation:

The complete question is:

Jolene wants to experiment with sugar cubes. Which of the following would cause only a chemical change with a sugar cube

The addition of acid to sugar (sucrose) is a known reaction that produces the chemical change of this carbohydrate into carbon, by a process of dehydration.

In the reaction of dehydration of sucrose with sulphuric acid - which is exothermic - the acid extracts water from the sugar molecule, producing gases, such as CO₂ and SO₂, which consumes the acid and converts the sucrose into carbon. The chemical reaction is:

C₁₂H₂₂O₁₁   +    H₂SO₄    +   1/2 O₂  → 11C + CO₂ + 12H₂O + SO₂

Sucrose + Sulfuric Ac. + Oxygen → Carbon + Carbon dioxide + water + sulfur dioxide.

This reaction involves only a chemical change of the sucrose, when converted into carbon.