Question

The chemical used to remove organic matter from the soil during mechanical analysis is

• A. CaCl$_2$
• B. HCl
• C. NaOH
• D. H$_2$O$_2$

Hint:

Mechanical analysis (particle size):
- H$_2$O$_2$: Removes organic matter.
- HCl: Removes carbonates.
- Dispersing agents: Sodium hexametaphosphate (calgon).

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
This question tests knowledge of soil mechanical analysis (particle size analysis).

Step 2: Detailed Explanation:
Hydrogen peroxide (H$_2$O$_2$) (D) is used to remove organic matter from soil during mechanical analysis.
It oxidizes organic matter, which is then removed, allowing for accurate determination of sand, silt, and clay percentages.
Other chemicals:
- CaCl$_2$ (A): Used for flocculation in the hydrometer method.
- HCl (B): Used to remove carbonates.
- NaOH (C): Not used in mechanical analysis.
Thus, H$_2$O$_2$ is used to remove organic matter.

Step 3: Final Answer:
Thus, the chemical used to remove organic matter is H$_2$O$_2$, which corresponds to option (D).
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