Question

Which chemical compound is used to reduce the acidity of the soil?
(A) Calcium hydroxide
(B) Ammonium sulphate
(C) Ammonium nitrate
(D) Ammonium chloride

Answer 1

Hint: When the acidity of the soil is increased, the growth of plants is affected. The soil acidity is due to the use of fertilisers, which supply nitrogen to the soil. The pH of soil above 5.5 is not harmful to plants. However, it is harmful to plants below 5.5.

Complete Step by Step Answer:
A soil is said to be acidic if it contains aluminium, chloride, or sulphate ions. The acidity of soil can be reduced by adding some basic substances to it. Whenever soil is found to be acidic, calcium hydroxide is used to neutralise its effect. This is because calcium hydroxide is alkaline in nature. Calcium hydroxide is commonly known as hydrated lime or slaked lime. It is mixed with soil, and then sprayed with water used to raise the pH of soil. Adding calcium hydroxide can help the plants grow healthier roots.
Correct Option: (A) Calcium hydroxide.

Note: Another chemical compounds that can be used to reduce the acidity of the soil are calcium oxide and calcium carbonate. Sometimes, eggshells are added to the compost to add calcium to the soil. However, an excess of calcium hydroxide can cause many problems for humans, like swelling in the throat, difficulty in breathing, abdominal pain, burning sensations in the eyes, nose, ears, lips, and tongue etc.