Which of the following is/are the example/examples of chemical change? 1. Crystallization of sodium chloride 2. Melting of ice 3. Souring of milk Select the correct answer using the code given below.

A chemical change results in the formation of one or more new substances with different chemical properties. A physical change alters the form or appearance of a substance but does not change its chemical composition. Crystallization of sodium chloride: This is a physical change. It involves the formation of solid sodium chloride crystals from a solution or molten state. The chemical identity of sodium chloride (NaCl) remains unchanged. Melting of ice: This is a physical change. Ice is solid water, and when it melts, it becomes liquid water. The chemical composition (H2O) remains the same; only its state of matter changes. Souring of milk: This is a chemical change. Souring occurs due to the action of bacteria (e.g., Lactobacillus) that convert lactose (milk sugar) into lactic acid. This process produces new chemical substances (lactic acid) that alter the milk's taste, smell, pH, and texture, making it an irreversible chemical transformation. Therefore, only the souring of milk is an example of a chemical change.