'लोहे पर जंग लगना' किस प्रकार का परिवर्तन है?

उत्तर: (A) रासायनिक / Chemical — Rusting is a chemical change: 4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O (hydrated iron oxide). It is irreversible, forms new substance (rust), and involves change in chemical composition. Painting and galvanizin...