Detailed Analysis of Soil Phase Parameters:

• Statement (I) is True: Porosity ($n$) is defined as the ratio of void volume ($V_v$) to total soil volume ($V$):
  $$n = \frac{V_v}{V} \times 100$$
  Because total volume consists of solids plus voids ($V = V_s + V_v$), the void volume $V_v$ is strictly less than total volume $V$ ($V_v \lt V$). Therefore, porosity is always less than 100% ($0 \lt n \lt 100\%$). It cannot exceed 100%.
• Statement (II) is False: Degree of saturation ($S$) is defined as:
  $$S = \frac{V_w}{V_v} \times 100$$
  For a completely oven-dry soil, the volume of water is zero ($V_w = 0$), so $S = 0\%$. Thus, the degree of saturation can indeed be zero percent ($0 \le S \le 100\%$).

Detailed Mineralogical Analysis of Clay Crystal Layer Thickness:
In soil mechanics and clay mineralogy, the structural thickness of the individual crystalline sheets/flakes increases in the following order:

• Montmorillonite (A): Smectite group (2:1 expanding lattice) with weak interlayer van der Waals bonding; individual flake thickness is smallest, approximately $0.96\text{ nm} \approx 1\text{ nm}$ ($10\text{ \AA}$), with lateral dimensions of $100\text{--}1000\text{ nm}$.
• Illite (D): Non-expanding 2:1 lattice bonded by non-exchangeable potassium ($K^+$) ions; flake thickness is about $3\text{ nm}$ ($30\text{ \AA}$).
• Chlorite (B): 2:1:1 lattice with an interlayer brucite-like octahedral sheet; flake thickness is approximately $3\text{--}5\text{ nm}$ ($30\text{--}50\text{ \AA}$).
• Kaolinite (C): Rigid 1:1 lattice held firmly by strong hydrogen bonding, stacking into thick plates; individual crystal thickness is largest, ranging from $50\text{ to } 100\text{ nm}$ ($500\text{--}1000\text{ \AA}$) or even up to $2000\text{ \AA}$.

Detailed Analysis of Soil Texture and Aeration:

• Statement (I) is Correct: By standard soil science and engineering definitions (USDA/ISSS), soil texture refers to the relative proportions by weight of the three soil separates: sand (2.0–0.05 mm or 2.0–0.02 mm), silt (0.05–0.002 mm or 0.02–0.002 mm), and clay (< 0.002 mm).
• Statement (II) is Correct: Fine-textured soils (clays and clay loams) are dominated by tiny micropores that retain water tenaciously and lack large macropores for free gas exchange. Consequently, their internal drainage is slow and aeration is typically medium to very poor.