Question

The mineral responsible for swelling of black cotton soil is ____

• A. Kaolinite
• B. Montmorillonite
• C. Illite
• D. Quartz

Hint:

Common clay minerals: \[ \boxed{ \begin{aligned} \text{Montmorillonite} &\rightarrow \text{Highest swelling} \text{Illite} &\rightarrow \text{Moderate swelling} \text{Kaolinite} &\rightarrow \text{Least swelling} \end{aligned} } \]

Answer 1

The Correct Option is B

Step 1: Recall the mineral composition of expansive soils. Black cotton soil is highly expansive because it contains the clay mineral montmorillonite.

Step 2: State the responsible mineral. Montmorillonite absorbs large amounts of water, causing significant swelling and shrinkage. Thus, \[ \boxed{\text{Montmorillonite}} \] is the correct answer. Hence, \[ \boxed{(B)} \] is the correct answer.