1. Take about 1 gm of quick lime (CaO) in a beaker.
2. Add 10 ml of water to this.
3. Touch the beaker with your finger.
4. The beaker is hot.
5. The reason is that the calcium oxide reacts with water and releases heat energy.
6. Calcium oxide dissolves in water producing colour less solution [Ca(OH)2],
7. Dip the red litmus paper in it.
8. Red litmus paper changes into blue colour.
9. We conclude that the solution obtained is a basic solution.
10. It is a chemical combination reaction.
CaO(s)+ H2O(I) → Ca(OH)2
