Question

Consider the statement(s) given below :
(A). The porosity of a material is dependent upon the arrangement of the particles, shape of grains and degree of assortment.
(B). The rhombohedral arrangement gives the maximum porosity.
(C). Transmissivity is expressed as sq. metres per day.

Choose the correct answer from the options given below:

• (B) and (C) only.
• (A) and (C) only.
• (A) and (B) only.
• (C) only.

Hint:

Remember:
- Cubic packing = Loosest \(\implies\) Max porosity (\(47.6\%\)).
- Rhombohedral packing = Tightest \(\implies\) Min porosity (\(26\%\)).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Porosity is the ratio of void volume to the total volume of a porous medium.
Transmissivity is a hydraulic parameter defining the rate of groundwater transmission through a unit width of an aquifer.

Step 3: Detailed Explanation:
1.

Statement (A): Porosity depends on the packing arrangement (cubic vs rhombohedral), the shape of the constituent grains (spherical vs angular), and the degree of assortment (uniformity of sizing). Well-sorted material has higher porosity than poorly sorted material where smaller grains fill the voids. Thus, Statement (A) is correct.
2.

Statement (B): Rhombohedral packing represents the most compact, tightest arrangement of spherical particles, which yields the

minimum theoretical porosity (about \(25.95\%\)).
Cubic packing represents the loosest arrangement, yielding the

maximum theoretical porosity (about \(47.64\%\)). Thus, Statement (B) is incorrect.
3.

Statement (C): Transmissivity (\(T\)) is the product of hydraulic conductivity (\(K\), m/day) and aquifer thickness (\(b\), m):
\[ T = K \cdot b \implies (\text{m/day}) \times \text{m} = \text{m}^2/\text{day} \] This is indeed expressed as square meters per day. Thus, Statement (C) is correct.

Step 4: Final Answer:
The correct option is 2, which corresponds to (A) and (C) only.