MCAER PG CET 2026 SOIL SCIENCE AND AGRIL CHEMISTRY

 

MCAER PG CET 2026: Soil Science

Time Remaining: 100s

1. According to the Hissink's method, the degree of base saturation is a measure of:

Soil buffering capacity Soil acidity relative to CEC Proportion of exchange sites occupied by basic cations Total potential acidity

Correct Answer: C
Explanation: Base saturation represents the percentage of the CEC occupied by basic cations (Ca, Mg, K, Na).

2. [PYQ 2022] Which clay mineral exhibits the highest interlayer expansion due to its low interlayer charge (0.6 to 0.9 per formula unit)?

Illite Vermiculite Montmorillonite Kaolinite

Correct Answer: C
Explanation: Montmorillonite (Smectite group) has high expansion because the units are loosely held by van der Waals forces.

3. The 'Law of Minimum' was modified into the 'Law of Restricting Factors' by:

J.V. Liebig F.F. Blackman Mitscherlich Wilcox

Correct Answer: B
Explanation: Blackman proposed that when a process is conditioned as to its rapidity by a number of separate factors, the rate of the process is limited by the pace of the slowest factor.

4. In submerged soils, the dominant form of Iron (Fe) present in the soil solution is:

Ferric (Fe3+) Ferrous (Fe2+) Magnetite Hematite

Correct Answer: B
Explanation: Submergence leads to anaerobic conditions where Fe3+ is reduced to the more soluble Fe2+.

5. [PYQ 2020] The ratio of the mass of water to the mass of dry soil is termed as:

Volumetric water content Gravimetric water content Bulk density Particle density

Correct Answer: B
Explanation: Gravimetric water content (θm) = Mass of water / Mass of oven-dry soil.

6. Which of the following is a non-expanding 2:1 type clay mineral?

Smectite Illite Vermiculite Chlorite

Correct Answer: B
Explanation: Illite is non-expanding because the interlayer space is tightly occupied by Potassium (K+) ions.

7. The 'Value' in the Munsell Soil Color Chart refers to:

Dominant spectral color Relative purity of color Lightness or darkness of color Strength of color

Correct Answer: C
Explanation: Value ranges from 0 (black) to 10 (white) in the Munsell system.

8. What is the pH of a soil solution where the H+ ion concentration is 0.00001 mol/L?

4 5 6 7

Correct Answer: B
Explanation: pH = -log[H+]. -log(10^-5) = 5.

9. The 'Zeta Potential' is associated with which soil property?

Soil texture Colloidal stability and flocculation Soil thermal conductivity Soil aeration

Correct Answer: B
Explanation: Zeta potential is the electrical potential at the slipping plane of a colloid; it determines if particles will repel or aggregate.

10. Which extractant is used for measuring 'Available Phosphorus' in neutral to alkaline soils (Olsen's Method)?

0.03 N NH4F + 0.025 N HCl 0.5 M NaHCO3 (pH 8.5) 1 N Ammonium Acetate 0.1 N HCl

Correct Answer: B
Explanation: Olsen's reagent (Sodium Bicarbonate) is standard for alkaline soils, while Bray's No. 1 is used for acidic soils.

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