Question

Humic substances are composed of:

• A. (A), (B) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D)
• D. (B), (C) and (D) only

Hint:

Remember that humic substances are chemically diverse and include multiple organic compounds such as phenols and acids.

Answer 1

The Correct Option is C

Humic substances are a complex mixture of many different acids containing phenolic and carboxylic groups. They are composed of phenols, quinones, carboxylic acids, and fatty acids. These components contribute to the chemical properties of humus in soil, aiding in nutrient retention and soil structure.

Answer 2

Conceptual approach:
Humic substances are not a single compound but a heterogeneous mixture built up during humification of plant and microbial residues. Structurally they carry aromatic rings (phenols and quinones formed from lignin breakdown) fused with aliphatic side chains bearing carboxylic and fatty acid groups. Because every one of these functional units, phenolic, quinone, carboxylic acid, and fatty acid, has been chemically identified in humic extracts, none of them can be excluded from the composition. This is why the option covering all four components together is the correct one, rather than any partial combination.