Which of the following represent a chemical change? 1. Magnetization of iron 2. Condensation of liquid 3. Burning of fuel 4. Rusting of iron Select the correct answer using the code given below : Code :

A chemical change involves the formation of new substances through chemical reactions, whereas a physical change alters only physical properties without changing the chemical composition [c1, t1]. Magnetization of iron is a physical change because the iron's chemical identity remains unchanged and the process is reversible [t1, t2]. Condensation of a liquid is also a physical change, as it is merely a phase transition from gas to liquid without altering molecular structure [t2, t7]. In contrast, burning of fuel (combustion) is a chemical change because it reacts with oxygen to produce new substances like carbon dioxide, water, and energy [c1, c3]. Rusting of iron is a chemical change where iron reacts with oxygen and moisture to form a new substance, iron oxide (rust) [c1, t1]. Therefore, only statements 3 and 4 represent chemical changes.

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