Which one of the following is NOT a chemical change ?

A physical change involves a change in physical properties, such as state or shape, without forming a new substance [4]. Melting of ice is a phase change where water transitions from a solid to a liquid state; the molecular composition remains H2O throughout the process, making it a physical change [1]. In contrast, a chemical change results in the formation of one or more new substances through chemical reactions [4]. Burning of coal is a chemical change (combustion) because it reacts with oxygen to produce carbon dioxide and heat [5]. Rusting of metal is a chemical change as it forms a new substance, iron oxide [4]. The reaction of an acid with a base is a neutralization reaction that produces new substances like salt and water, accompanied by temperature changes, which are indicators of a chemical reaction [6].

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > In a Nutshell > p. 68
2. [4] https://drklbcollege.ac.in/wp-content/uploads/2020/03/Changes-in-energy-are-always-accompanied-by-a-particular.pdf
3. [5] https://sathee.iitk.ac.in/article/chemistry/chemical-and-physical-change-examples/
4. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > 5.3.1 Rusting > p. 62
5. [6] https://www.education.gov.pg/FODE/courses/Science/Grade%2011/chemistry/Types%20of%20Chemical%20Reactions.pdf