Dissolution of sugar:
1. When sugar is dissolved in water it disappears. It we taste the solution, the sugar is still present in dissolved form.
2. If water is evaporated we get back the sugar.
3. So it is a physical and reversible change.
Burning of sugar:
1. Fire activates a chemical reaction between sugar and oxygen. The oxygen in the air reacts with the sugar as the chemical bonds broke.
2. Energy is released in the form of smoke.
3. So, burning a sugar is a chemical change.
