Among the given items, burning of paper is an example of a chemical change. All the other are examples of physical change. Physical change is any change that only transforms the substance's physical properties, but chemical change results in change in the chemical structure of the substances involved. A chemical reaction also cannot be reversed. When paper burns, the cellulose in the air reacts with the oxygen to form carbon dioxide and water. Also, the action of the burning paper cannot be reversed. In all other changes given here, a new substance is formed but without any change in the chemical structure of the substances involved.