Permanent negative charges in soils primarily result from isomorphous substitution, where one ion is replaced by another of similar size but different charge (e.g., Al³⁺ replacing Si⁴⁺). This occurs within the clay mineral lattice. The idea that permanent charge comes from crystal edges is incorrect—it is edge charges that are variable, not permanent.
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27 Mins English English100 Questions100 Marks120 Mins English English75 Questions300 Marks90 Mins English(i) Very dark, cracking clay-dominated soils;
(ii) locally called regur, karail, and bhal;
(iii) high clay varying from 30–60%, base-rich;
(iv) occur in Maharashtra, Madhya Pradesh, Gujarat, Rajasthan, Chhattisgarh and some parts of Karnataka and T.N. __________- is called
[A] Black Soils
[B] Alluvial Soils
[C] Red Soils
[D] Laterite and Lateritic Soils
Choose the correct answer from the options given below:
The following is the list of pesticides:
[a] B.H.C.
[b] D.D.T.
[c] NaCN
[d] Heptachlor
[e] Carbendazim
Choose the correct answer from the options given below:
Objective of GIS
[A] Maximizing the efficiency of planning and decision-making.
[B] Providing efficient means for data distribution and handling.
[C] Elimination of redundant database – minimize duplication.
[D] Capacity to integrate information from many sources.
Choose the most correct answer from the options given below:
| List-I (Land Capability Classes) |
List-II (Colour) |
| (A) Class II |
(I) Green |
| (B) Class IV |
(II) Yellow |
| (C) Class III |
(III) Brown |
| (D) Class I |
(IV) Pink |
Match List-I with List-II
List-I (Characteristic)
(A) Si is replaced by Al³⁺ ions
(B) Attachment of Ca²⁺ on clay surface
(C) Na⁺ replacing other cations on clay surface
(D) H dissociated from hydroxyl ions on clay surface
List-II (Terminology)
(I) Ionic double layer
(II) pH dependent charge
(III) Dispersion of clay
(IV) Isomorphous substitution
Choose the correct answer from the options given below:
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