Materials:
1. A penny (preferably dirty and dull coin)
2. Lemon
3. Glass
Instruction:
1. Squees lemon juice into a glass.
2. Soak the coin in the lemon juice and take it out in a few minutes.
Explanation:
Copper coin often look dull and dirty because oxygen in the air reacts with the copper, making a copper oxide coating. The acid in the lemon juice reactions with the oxide and removes it, leaving a shiny copper coin.
