Which of the following is an example of a chernical change?

Boiling water

Burning paper

Dissolving sugar in water

Melting gold

the chemical change occur in burning paper.

boiling water does not make any chemical change

melting gold "

dissolving sugar in water "

in these examples the reactant remains as the same, even if you melt gold it is gold itself, it only change its state.

Burning paper.

Explanation:

A chemical change is a change that changes the molecular structure of the substance you are changes. Boiling water would make water vapour, which is still water thus it is a physical change. Dissolving sugar in water is still sugar in water thus it is a physical change. Melting gold makes liquid gold which is still gold thus it is a physical change. Burning paper however changes from paper to ash and smoke, which are different on the molecular level, therefore it is a chemical change.