Science — AI-generated practice question

A farmer would treat his fields with quicklime (CaO) or slaked lime [Ca(OH)₂] when the soil is too acidic (i.e., has a low pH).

Reason: CaO and Ca(OH)₂ are basic in nature. When added to acidic soil, they neutralise the excess acid present in it:

$$\text{CaO} + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2$$

Ca(OH)₂ then neutralises soil acids, raising the pH to a level suitable for crop growth. This process is called treatment of soil with bases to correct soil acidity.

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• The key concept tested is neutralisation — a base neutralises an acid.
• Examiner expects: (1) identification of soil condition (acidic/low pH), (2) reason that CaO/Ca(OH)₂ is basic and neutralises the acid in soil.
• Mentioning the reaction of CaO with water to form Ca(OH)₂ earns an extra point.
• Do not confuse with alkaline soil — lime is added only to acidic soil.