Answer:1. To obtain useful substancesExample/Industry: Salt production – Seawater is evaporated to separate salt crystals from water.2. To remove impuritiesExample/Industry: Water treatment plants – Filtration is used to separate dirt and harmful particles from drinking water.3. To recycle and reuse materialsExample/Industry: Waste management/recycling centers – Materials like metals, plastics, and paper are separated for recycling.