Question

According to Indian Standard Soil Classification choose the correct option for different soil particle size in descending order A. Boulder \(>\) Sand \(>\) Gravel \(>\) Silt B. Sand \(>\) Silt \(>\) Clay \(>\) Gravel C. Cobbles \(>\) Clay \(>\) Silt \(>\) Sand D. Gravel \(>\) Sand \(>\) Silt \(>\) Clay Choose the correct answer from the options given below:

• A. C Only
• B. B Only
• C. D Only
• D. A Only

Hint:

Descending particle size order: \[ \boxed{ \text{Boulder} > \text{Cobbles} > \text{Gravel} > \text{Sand} > \text{Silt} > \text{Clay} } \] Clay particles are the finest soil particles.

Answer 1

The Correct Option is C

Concept: In Indian Standard Soil Classification System (IS classification), soil particles are arranged according to decreasing particle size. The major categories are:
• Boulder
• Cobbles
• Gravel
• Sand
• Silt
• Clay Descending order means arrangement from larger particle size to smaller particle size.

Step 1: Writing standard descending order of soil particles. The correct descending order is: \[ \boxed{ \text{Boulder} > \text{Cobbles} > \text{Gravel} > \text{Sand} > \text{Silt} > \text{Clay} } \] This sequence is universally used in soil mechanics.

Step 2: Checking Statement A. Statement A: \[ \text{Boulder} > \text{Sand} > \text{Gravel} > \text{Silt} \] This is incorrect because: \[ \boxed{ \text{Gravel particles are larger than sand particles} } \] Hence: \[ \boxed{ \text{Statement A is incorrect} } \]

Step 3: Checking Statement B. Statement B: \[ \text{Sand} > \text{Silt} > \text{Clay} > \text{Gravel} \] Incorrect because gravel should come before sand. Thus: \[ \boxed{ \text{Statement B is incorrect} } \]

Step 4: Checking Statement C. Statement C: \[ \text{Cobbles} > \text{Clay} > \text{Silt} > \text{Sand} \] Incorrect because clay is the smallest particle. Therefore: \[ \boxed{ \text{Statement C is incorrect} } \]

Step 5: Checking Statement D. Statement D: \[ \text{Gravel} > \text{Sand} > \text{Silt} > \text{Clay} \] This follows proper descending order. Thus: \[ \boxed{ \text{Statement D is correct} } \]

Step 6: Checking options carefully. Option (A): Incorrect because C is false. \[ \boxed{ \text{Option (A) is incorrect} } \] Option (B): Incorrect because B is false. \[ \boxed{ \text{Option (B) is incorrect} } \] Option (C): Correct because D alone is correct. \[ \boxed{ \text{Option (C) is correct} } \] Option (D): Incorrect because A is false. \[ \boxed{ \text{Option (D) is incorrect} } \] Final Conclusion: Correct descending order among the given statements is: \[ \boxed{ \text{Gravel} > \text{Sand} > \text{Silt} > \text{Clay} } \] Hence the correct answer is: \[ \boxed{ (C) } \]