Detailed Explanation:

✅ Statement 1 – Incorrect: Crystallization of sodium chloride is a physical change; NaCl changes from dissolved to solid state without altering its chemical composition.
✅ Statement 2 – Incorrect: Melting of ice is a physical change; H₂O molecules transition from solid to liquid state while maintaining the same chemical structure.
✅ Statement 3 – Correct: Souring of milk is a chemical change; bacteria convert lactose into lactic acid, creating new substances and irreversibly altering the chemical composition.