The pH of soil A is 7.5 while that of soil B is 4.5. Which of the two soils, A or B, should be treated with powdered chalk to adjust its pH and why?

8 Name the scientist who developed the pH scale. 9 Name the indicator which can give us an idea of how strong or weak an acid or base is. 11 What is the name of the indicator which can be used for testing the pH of a solution? 12 What colour will universal indicator show if you add it to the following substances?

(a) potassium hydroxide, pH = 12

(b) sodawater, pH = 5

(c) sulphuric acid, pH = 2