Match List-I with List-II
Choose the correct answer from the options given below:
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To quickly solve soil analysis match-ups:
- Walkley-Black is always for Organic Carbon.
- Kjeldahl is always for Nitrogen.
- Hydrometer is for mechanical analysis of Soil Texture.
Step 1: Understanding the Concept:
Standardized laboratory analytical techniques are used to evaluate the physical, chemical, and biological properties of soil.
Each technique relies on a specific chemical reaction or physical principle. Step 2: Detailed Explanation:
Let us match the laboratory methods with their corresponding determinations:
- (A). Gravimetric method: This is the direct, standard method for determining soil moisture content.
It involves weighing a moist soil sample, drying it in an oven at \( 105^\circ\text{C} \) until it reaches a constant weight, and reweighing it to calculate the mass of water lost.
Thus, (A) matches with (IV).
- (B). Hydrometer method: This is a physical sedimentation technique based on Stokes' Law, used to determine soil texture (the relative proportions of sand, silt, and clay).
Thus, (B) matches with (III).
- (C). Walkley & Black method: This is a rapid wet-combustion method used to estimate soil organic carbon.
It involves oxidizing organic carbon with potassium dichromate (\(\text{K}_2\text{Cr}_2\text{O}_7\)) in the presence of concentrated sulfuric acid.
Thus, (C) matches with (II).
- (D). Kjeldahl method: This is the classical chemical method for determining total nitrogen in soil or organic matter.
It involves digesting the sample with concentrated sulfuric acid to convert organic nitrogen to ammonium sulfate, followed by distillation and titration.
Thus, (D) matches with (I).
This gives the matching sequence: (A) - (IV), (B) - (III), (C) - (II), (D) - (I). Step 3: Final Answer:
The correct matching sequence is (A) - (IV), (B) - (III), (C) - (II), (D) - (I).
