You Find That the CEC of a Sandy Loam Soil

question 27

Multiple Choice

You find that the CEC of a sandy loam soil at pH 5.0 is 8 cmol_c/kg and at pH 8.2 it is 14 cmol_c/kg. What is the most likely reason for this difference?

• A) increase in the pH-dependent charges on 1:1 type silicate clays
• B) removal of Al³⁺ ions from the exchange complex at higher pH.
• C) ionization of carboxyl and phenolic groups to release H⁺ ions
• D) removal of Al atoms from tetrahedral layers at low pH.
• E) replacement of trivalent Al³⁺ ions with divalent Ca²⁺ ions at high pH.

Recognize the significance of cohort effects on developmental differences.

Differentiate between cross-sectional, longitudinal, and sequential research designs.

Explain the concept of selective attrition and its impact on research studies.

Understand the concept of object permanence and its developmental significance.

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