In which one of the following cases do both physical and chemical changes take place?

The burning of a candle involves both physical and chemical changes simultaneously. The heat from the flame causes the solid wax to melt into liquid wax, which is a physical change because the chemical identity of the wax remains unchanged [3]. Some of this liquid wax is then drawn up the wick, evaporates, and reacts with oxygen in the air to undergo combustion. This combustion process is a chemical change because it produces new substances such as carbon dioxide, water vapor, heat, and light [3]. In contrast, freezing of water is purely a physical change of state [1]. Cooking of food and rusting of iron are primarily classified as chemical changes because they result in the formation of new substances with different chemical properties [3]. Therefore, only the burning of a candle represents a combination of both change types.

Sources

1. [3] https://drklbcollege.ac.in/wp-content/uploads/2020/03/Changes-in-energy-are-always-accompanied-by-a-particular.pdf
2. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > 5.4 Can Physical and Chemical Changes Occur in the Same Process? > p. 65