Question

Arrange the following in decreasing order of Basal Spacing:
(A) Kaolinite
(B) Montmorillonite
(C) Illite
(D) Vermiculite
Choose the correct answer from the options given below:

• A. (A), (B), (D), (C)
• B. (A), (B), (C), (D)
• C. (B), (A), (D), (C)
• D. (B), (D), (C), (A)

Hint:

Basal spacing order: Montmorillonite > Vermiculite > Illite > Kaolinite.

Answer 1

The Correct Option is D

Step 1: Basal spacing depends on how tightly the clay layers are held together, weaker interlayer bonding gives larger spacing.
Step 2: Montmorillonite (2:1, expanding, weak bonds) has the widest spacing, Vermiculite (2:1, moderate bonds) is next.
Step 3: Illite (2:1, K+ locked layers) has a smaller spacing, and Kaolinite (1:1, H-bonded) has the smallest.
Step 4: This gives the order Montmorillonite > Vermiculite > Illite > Kaolinite, so the correct option is (B), (D), (C), (A).