Which one among the following is a physical process ?

A physical process or change is one where a substance undergoes a change in its physical properties (like state or shape) without forming a new chemical substance [2]. Sublimation of iodine is a physical process because it involves a change of state from solid directly to gas without altering the chemical identity of iodine. In contrast, the other options involve chemical changes where new substances are formed through chemical reactions. Digestion of food involves breaking down complex molecules like carbohydrates into simpler substances like glucose [5]. Corrosion or rusting of metal is a chemical change resulting in the formation of new substances like iron oxide [1]. The production of hydrogen from an acid involves a chemical reaction where a metal displaces hydrogen, forming a salt and hydrogen gas [6].

Sources

1. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > In a Nutshell > p. 68
2. [4] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > p. 1
3. [5] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > QUESTIONS > p. 7
4. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 5: Changes Around Us: Physical and Chemical > 5.3.1 Rusting > p. 62
5. [3] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Activity 2.3 > p. 20
6. [6] https://sathee.iitk.ac.in/hi/ncert-books/class-10/knowledge-route-10/knowledge-route-10-chemistry/nitin_knowledge-route-class10-chem1-2_merged2/