Basic Physics

• Water Filtration Media:
• Municipal and industrial granular bed filters utilize high-purity silica sand, crushed anthracite coal, and dense garnet sand to construct single-media or multi-media dual filter beds.
• Crushed rock is too coarse and irregular for fine granular filtration, being reserved for biological trickling filters and drain packings. (Correct answer: Option 2)

• Assertion (A) is True: Soil bulk density ($\rho_b = \frac{M_s}{V_t}$) is always numerically smaller than soil particle density ($\rho_s = \frac{M_s}{V_s}$) for any natural undisturbed soil.
• Reason (R) is True: Total soil volume ($V_t$) comprises both the solid mineral volume ($V_s$) and the pore volume ($V_p$), such that $V_t = V_s + V_p \gt V_s$. Dividing solid dry mass by a larger total volume necessarily yields a lower density value.
• Relationship: The inclusion of pore space in total soil volume directly explains why bulk density is lower than particle density; thus, Reason (R) correctly explains Assertion (A).
• Conclusion: Both (A) and (R) are true and (R) is the correct explanation of (A) (Option 1).

Correct option: (1) Both (A) and (R) are true and (R) is the correct explanation of (A)

• Hagen-Poiseuille Law Applicability:

• Fluid Mechanics Conditions:
• Applies strictly to the steady, fully developed laminar flow ($Reynolds\ number \lt 2000$) of incompressible Newtonian fluids through circular cylindrical conduits of uniform cross-section. (Correct answer: Option 3)