| Acids | Bases |
| 1. An acid is a substance which gives H3O+ ions in water solution. | 1. A base is a solution which contains OH group in water solution gives hydroxyl ions OH– . |
| 2. Acids are sour in taste. | 2. Bases are bitter in taste. |
| 3. Acid turns blue litmus to red. | 3. Bases turn red litmus to blue. |
| 4. The orange colour of methyl orange indicator changes to red in acid medium. | 4. The orange colour of methyl orange indicator changes to yellow in bases medium. |
| 5. Acid are formed when non-metal oxides are dissolved in water. | 5. Bases are formed when metal oxides are dissolved in water. |
| 6. pH value of acid is less than 7. | 6. pH value of base is greather than 7. |