* Elements are pure substances that cannot be broken down further (like oxygen, hydrogen, or gold).

* Compounds are formed when two or more elements combine chemically in a fixed ratio (like water, H₂O).

* Mixtures are combinations of two or more substances that are not chemically bonded. The substances in a mixture retain their individual properties.

River water contains:

* Water (H₂O): The primary component, a compound.

* Dissolved minerals: Salts, calcium, magnesium, and others.

* Organic matter: Decomposed plants and animals.

* Gases: Oxygen, carbon dioxide, and nitrogen.

* Suspended particles: Sand, silt, and other debris.

These components are not chemically bonded, and their proportions can vary depending on the location and time of year. This makes river water a heterogeneous mixture.