* Compounds are formed when two or more different elements chemically combine.

* Milk is a mixture of various substances, including fats, proteins, and water.

* Soil is a complex mixture of minerals, organic matter, and water.

* Gold is an element, meaning it's made up of only one type of atom.

* Water is a compound formed from the chemical combination of hydrogen (H) and oxygen (O) atoms in a ratio of 2:1 (H₂O).