Science — AI-generated practice question

Problem faced by crops:
Soil with pH 4 is highly acidic. Most crops cannot grow well in such acidic soil because nutrients become unavailable and minerals like aluminium and manganese may reach toxic levels, hampering healthy plant growth.

What should be added and why:
The farmer should add quick lime (calcium oxide), slaked lime (calcium hydroxide), or chalk (calcium carbonate) to the soil. These are basic substances that neutralise the excess acid in the soil, raising the pH to a range suitable for healthy crop growth.

Source: Chapter 2, Section 2.3.1 – Importance of pH in Everyday Life

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• The question tests knowledge of soil pH and its agricultural importance from Section 2.3.1.
• Key point: pH 4 = highly acidic → unfavourable for crops.
• The textbook specifically states farmers treat acidic soil with quick lime / slaked lime / chalk — name all three for full marks.
• Mention neutralisation as the reason; that's the chemical concept being tested.
• 3-mark split: 1 mark for identifying the problem, 1 mark for naming the substance(s), 1 mark for explaining why (neutralisation).