Question

The most common 1:1 type of clay mineral in soil is--

• A. Montmorillonite
• B. Kaolinite
• C. Vermiculite
• D. Halloysite

Hint:

Kaolinite = 1:1 clay mineral, low shrink-swell, common in weathered soils.

Answer 1

The Correct Option is B

Step 1: Recall that clay minerals are classed by sheet ratio, 1:1 means one tetrahedral + one octahedral sheet per unit layer.
Step 2: Montmorillonite and Vermiculite are 2:1 minerals (two tetrahedral sheets around one octahedral sheet), so eliminate them.
Step 3: Halloysite is a minor, hydrated 1:1 variant, not the most common one.
Step 4: The correct answer is \[ \boxed{\text{Kaolinite}} \]