Under what soil conditions do you think a farmer would treat the soil of his fields with quicklime (calcium oxide), or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?

27 The pH of a cold drink is 5. What will be its action on blue and red litmus solutions? 27 The pH values of three acids A, B and having equal molar concentrations are 5.0, 2.8 and 3.5 respectively.

Arrange these acids in order of the increasing acid strengths.

29 Which acid is produced in our stomach? What happens if there is an excess of acid in the stomach? How can its effect be cured? 30 The soil in a field is highly acidic. Name two materials which can be added to this soil to reduce its acidity. Give the reason for your choice.