Clay particles in soil have the diameter of

Correct option is A

The correct answer is (A) < 0.002 mm

Explanation:
• Soil texture is determined by the relative proportions of sand, silt, and clay. These are defined by rigid size limits established by systems like the International Society of Soil Science (ISSS) or the USDA.
• Clay consists of the smallest particles in the soil, with a diameter of less than 0.002 mm (or < 2 microns).
• Because of their tiny size, clay particles have a very high specific surface area, which gives them unique properties like high water-holding capacity, plasticity, and chemical reactivity (Cation Exchange Capacity).
• Clay minerals are usually secondary minerals formed from the weathering of primary minerals.

Information Booster:
•
• ISSS Classification: Coarse Sand (2.0-0.2 mm), Fine Sand (0.2-0.02 mm), Silt (0.02-0.002 mm), Clay (< 0.002 mm).
• USDA Classification: Sand (2.0-0.05 mm), Silt (0.05-0.002 mm), Clay (< 0.002 mm).
• Despite differences in silt/sand boundaries, both systems agree that the upper limit for clay is 0.002 mm.

Additional Knowledge:
• 0.02 – 0.002 mm (Option B): This is the range for Silt according to the ISSS system.
• 0.02 – 0.2 mm (Option C): This is Fine Sand.
• 2.0 – 0.20 mm (Option D): This is Coarse Sand.