1.  Physical change: A change in which a substance undergoes a change in its physical properties.

2.  Rust: When pieces of iron is left in the open for sometime, it acquires a film of brownish substance which is called rust.

3.  Rusting: The process in which rust is formed.

4.  Chemical change: A change in which one or more new substances are formed.

5.  Chemical reaction: A chemical change is called chemical reaction.

6.  Galvanisation: The process of depositing a layer of zinc on iron is called galvanization.

7.  Crystallisation: The process by which large crystals of pure substances are formed from their solutions.