Question

When you travel in certain parts of India, you will notice red soil. What is the main reason for this colour ?

• A. Abundance of magnesium
• B. Accumulated humus
• C. Presence of ferric oxides
• D. Abundance of phosphates

Answer 1

The Correct Option is C

Step 1 — About red soil:
Red soils are commonly found in parts of southern, eastern, and central India. These soils are formed by the weathering of ancient crystalline and metamorphic rocks, particularly granites and gneisses.

Step 2 — Reason for red colour:
The distinctive red colour of this soil is due to the presence of iron compounds. When iron in the soil oxidises (reacts with oxygen), it forms ferric oxides, which impart the characteristic red hue.

Step 3 — Supporting features:
- When hydrated, the soil may appear yellowish.
- Red soil is typically poor in nitrogen, phosphorus, and organic matter, but it is rich in iron content.
- It is found extensively in states like Tamil Nadu, Karnataka, Andhra Pradesh, Odisha, Chhattisgarh, and parts of Jharkhand and Maharashtra.

Step 4 — Conclude:
Therefore, the red colour of red soil is mainly due to the presence of ferric oxides.

Answer: The correct option is (C) : Presence of ferric oxides.