Question

Arrange the soil particles in the ascending order of its diameter (mm)
(A) silt
(B) clay
(C) fine sand
(D) coarse sand
Choose the correct answer from the options given below :

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

Hint:

To remember soil separate sizing, keep the critical boundary limits in mind:
- Clay: $< 0.002\text{ mm}$
- Silt: $0.002 - 0.02\text{ mm}$
- Fine Sand: $0.02 - 0.2\text{ mm}$
- Coarse Sand: $0.2 - 2.0\text{ mm}$

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Soil texture is determined by the relative proportion of different mineral soil separates (sand, silt, clay).
According to the International Soil Science Society (ISSS) and the United States Department of Agriculture (USDA) systems, these soil separates are classified strictly based on their physical diameter ranges.

Step 3: Detailed Explanation:
Let us analyze the diameter ranges for each soil separate under the ISSS classification system:
- (B) Clay: This is the smallest soil separate, with a diameter of less than 0.002 mm ($< 0.002\text{ mm}$).
- (A) Silt: This separate consists of medium-sized particles, with a diameter ranging from 0.002 mm to 0.02 mm ($0.002 - 0.02\text{ mm}$).
- (C) Fine sand: Consists of larger particles, with a diameter ranging from 0.02 mm to 0.2 mm ($0.02 - 0.2\text{ mm}$).
- (D) Coarse sand: Consists of the largest primary soil particles, with a diameter ranging from 0.2 mm to 2.0 mm ($0.2 - 2.0\text{ mm}$).
Arranging these soil separates in ascending order of their diameters (from smallest to largest):
\[ \text{Clay (B)} < \text{Silt (A)} < \text{Fine sand (C)} < \text{Coarse sand (D)} \]
This corresponds to the sequence: (B), (A), (C), (D).
This matches Option (A).

Step 4: Final Answer:
The correct ascending order of soil particle diameters is (B), (A), (C), (D).