Which one of the following is an example of chemical change ?

A chemical change occurs when a substance's composition is altered, resulting in the formation of one or more new substances [1]. Burning of paper is a combustion reaction where paper reacts with oxygen to produce new substances such as ash, carbon dioxide, and water vapor [2]. This process is irreversible and involves the breaking and forming of chemical bonds. In contrast, the magnetization of soft iron is a physical change because it only involves the alignment of magnetic domains without altering chemical composition. Dissolution of cane sugar in water is a physical change as the sugar molecules disperse but retain their chemical identity and can be recovered by evaporation. Similarly, the preparation of ice cubes is a physical change (freezing) involving only a change in the state of matter from liquid to solid [1].

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > In a Nutshell > p. 68
2. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > 5.3.2 Combustion > p. 62