- Iron is a kind of metal
- Nails are often made of iron
- Hence, nails are made of metal

- Nails are made of metal
- Metals in contact with water and oxygen will rust
- Hence, nails in contact with water and oxygen will rust

- Nails in contact with water and oxygen will rust
- Rust forming is a kind of chemical change
- Therefore, nails rusting is a kind of chemical change

- Nails rusting is a kind of chemical change
- Chemical change is a kind of chemical reaction
- Therefore, nails rusting is a kind of chemical reaction

So, nails rusting is a kind of chemical reaction
Which is an example of a chemical reaction?
- Metals in contact with water and oxygen will rust 
- Iron is a kind of metal 
- Nails are often made of iron 
- Rust forming is a kind of chemical change 
- Chemical change is a kind of chemical reaction