Question

A soil scientist analysing a particular soil sample finds that its cation exchange capacity (CE

Q: Answer-A soil scientist analysing a particular soil sample finds that its cation exchange capacity (CEC) is...

Kaolinite, a 11 type clay mineral, consists of tightly bonded layers held together by hydrogen bonding, resulting in a comparatively small specific surface area and very low layer charge compared with 21 type clay minerals such as montmorillonite or illite this explains the much lower cation exchange capacity of kaolinite-dominated soils.

C is unusually low despite a moderately fine texture, and further investigation reveals that the soil's clay fraction is dominated by kaolinite rather than montmorillonite or illite. Which characteristic of kaolinite, a 1:1 type clay mineral, best explains this comparatively low CEC despite the soil's fine texture?

A Kaolinite has a very large surface area and high layer charge

B Kaolinite is highly soluble in water and dissolves before CEC can be measured

C Kaolinite has a comparatively small surface area and very low layer charge due to its tightly bonded 1:1 structure

D Kaolinite contains no aluminium or silicon at all

E Kaolinite always increases CEC regardless of soil texture

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