Question

1. chemical changes questions 6) name 5 elements - symbols 7) name 2 compounds 8) what is a substance? 9) 2 kinds of mixtures?

Explanation:

1. Elements are pure substances made of one - type of atom. Common elements and their symbols: Hydrogen (H), Oxygen (O), Carbon (C), Nitrogen (N), Sodium (Na).
2. Compounds are substances made of two or more different elements chemically combined. Examples: Water (H₂O), Carbon dioxide (CO₂).
3. A substance is a form of matter that has a definite composition and distinct properties.
4. The two kinds of mixtures are homogeneous mixtures (uniform composition throughout, like salt - water solution) and heterogeneous mixtures (non - uniform composition, like a mixture of sand and water).

Answer:

1. Hydrogen (H), Oxygen (O), Carbon (C), Nitrogen (N), Sodium (Na)
2. Water (H₂O), Carbon dioxide (CO₂)
3. A form of matter with definite composition and distinct properties.
4. Homogeneous mixtures, Heterogeneous mixtures