1. Pure Substances: These are substances that have a fixed chemical composition and properties. They cannot be separated into simpler substances by physical means. Examples include elements like gold (Au) and compounds like water (H₂O).
2. Mixtures: These are combinations of two or more pure substances that are not chemically bonded. They can be separated by physical means like filtration, distillation, or evaporation. Examples include saltwater (salt dissolved in water) and air (a mixture of gases).
