Given below are two statements, one is labeled as Assertion (A), and the other one is labeled as Reason (R).

Assertion (A): Humic acids are more resistant than fulvic acid.

Reason (R): Humic acids have low molecular weight and simple structure than fulvic acids.

In light of the above statements, choose the correct answer from the options given below.

Correct option is C

Explanation of the Correct Option (c): (A) is true but (R) is false
Why Assertion (A) is TRUE:
· Humic acids are:
· More complex in structure
· Have higher molecular weight
· Due to this complexity, they are:
· More resistant to microbial decomposition
· More stable in soil compared to fulvic acids
· Hence, humic acids are more resistant than fulvic acids.
Why Reason (R) is FALSE:
· Humic acids do not have low molecular weight.
· In reality:
· Humic acids → higher molecular weight, complex structure
· Fulvic acids → lower molecular weight, simpler structure
· Therefore, the reason incorrectly describes humic acids.
Explanation of Other Options
Option (a): Both (A) and (R) are true and (R) explains (A)
· Incorrect because:
· Reason (R) is factually wrong.
Option (b): Both (A) and (R) are true but (R) is not the explanation
· Incorrect because:
· (R) itself is false.
Option (d): (A) is false but (R) is true
· Incorrect because:
· Assertion (A) is correct.
Key Points Related to the Question
· Humic substances: Humic acid, Fulvic acid, Humin
· Humic acid:
· Dark coloured
· Higher molecular weight
· Insoluble in acidic medium
· More resistant to decomposition
· Fulvic acid:
· Lighter coloured
· Lower molecular weight
· Soluble at all pH