What is the difference between a physical change and a chemical change?

Physical change: No new substance is formed. Change is usually reversible. Matter changes in form/state. Chemical change: New substance with different properties is formed. Usually irreversible. Energy is absorbed or released. Categorising your examples: Tearing paper = PHYSICAL (paper still has same chemical composition, just smaller pieces). Burning paper = CHEMICAL (new substances: carbon dioxide, water vapour, ash). Melting ice = PHYSICAL (still H2O, just liquid state — reversible by freezing). Rusting iron = CHEMICAL (iron + oxygen + water forms iron oxide, a new substance with different properties). Dissolving sugar in water = PHYSICAL (sugar molecules disperse but do not change chemically — you can recover sugar by evaporating water).