Question

The specific yield of a fine-grained material such as clay and shale is

• A. Less than or equal to 5%
• B. 6 to 10%
• C. 11 to 15%
• D. 16 to 25%

Hint:

Specific yield is the volume of water that drains out of a saturated material under gravity, expressed as a percentage of the total volume. It tells us how much of the stored water can actually be extracted.

Answer 1

The Correct Option is A

Step 1: Meaning of specific yield.
Specific yield is the part of the stored water that actually drains out of a saturated material under gravity, given as a percentage of the total volume.

Step 2: Role of grain size.
Coarse materials such as gravel and sand have large connected pores, so most of their water drains freely and their specific yield is high.

Step 3: Behaviour of fine material.
Fine grained materials like clay and shale have very tiny pores. The water clings to the grain surfaces by molecular attraction and is held back.

Step 4: Effect on draining.
Because almost all the water is held tightly, very little drains out under gravity, so the specific yield is very small.

Step 5: Pick the range.
Such a small drainable fraction means the specific yield is only a few percent, that is less than or equal to about 5 percent.

Step 6: Answer.
So the specific yield of clay and shale is less than or equal to 5 percent.

\[ \boxed{\le 5\%} \]