Materials:

1. Red litmus paper 

2. Blue litmus paper 

3. Sodium hydroxide 

4. Hydrochloride acid 

5. Pipette 

6. 4 Test tubes 

Steps:
1. Rip the litmus papper in half and put half in each tube 
2. Add 3 drops of hydrochloride acid to the blue litmus papper in test tube 1
3. Add 3 drops of hydrochloride acid to the red litmus paper in test tube 2 
4.Add 3 drops of Sodium hydroxide in the blue litmus paper in test tube 3 
5. Add 3 drops of Sodium bydroxide in the red litmus paper in test tube 4