New substances are formed by chemical reactions. When elements react together to form compounds their atoms join to other atoms using chemical bonds. For example, iron and sulfur react together to form a compound called iron sulfide. hence, formation of compound is called chemical change

Formation of a compound is a chemical change.

Explanation:
A compound is a substance formed by the chemical combination of two or more elements in fixed proportions. When elements combine chemically to form a compound, the resulting chemical reaction involves the breaking and making of chemical bonds. This process is known as a chemical change.

1. Definition of a compound:
- A compound is a pure substance made up of two or more elements chemically combined in a fixed ratio.
- The elements in a compound are held together by chemical bonds.

2. Characteristics of a chemical change:
- Formation of a new substance with different properties.
- Irreversible change.
- Involves the breaking and forming of chemical bonds.
- Energy is usually absorbed or released during the reaction.
- The reaction is accompanied by a change in color, odor, temperature, or state of matter.

3. Formation of a compound as a chemical change:
- When elements combine to form a compound, the atoms rearrange themselves to form new chemical bonds.
- This rearrangement is a chemical change because the original atoms lose their original properties and acquire new properties in the compound.
- For example, when hydrogen gas (H2) combines with oxygen gas (O2) to form water (H2O), a chemical change occurs. The hydrogen and oxygen atoms rearrange themselves to form new bonds in the water molecule.

4. Distinction from physical changes:
- Physical changes only involve a change in the physical properties of a substance, such as shape, size, or state of matter, without the formation of a new substance.
- In contrast, the formation of a compound involves the creation of a new substance with different properties, which is a characteristic of a chemical change.

In conclusion, the formation of a compound is a chemical change because it involves the rearrangement of atoms and the formation of new chemical bonds, resulting in the creation of a new substance with different properties.

Because A New Substance is Formed In This Chemical Reaction Thus, The Formation of a compound is A Chemical Change