Question

Match List-I with List-II 
\[\begin{array}{|l|l|} \hline \text{List I Content of humus} & \text{List II Percentage of contents} \\ \hline \text{(A) Carbon} & \text{(I) 35-40\%} \\ \hline \text{(B) Oxygen} & \text{(II) ~5\%} \\ \hline \text{(C) Hydrogen} & \text{(III) 55-60\%} \\ \hline \text{(D) Nitrogen} & \text{(IV) 15\%} \\ \hline \end{array}\]
Choose the correct answer from the options given below: 
 

• (A) - (III), (B) - (I), (C) - (II), (D) - (IV)
• (A) - (III), (B) - (II), (C) - (IV), (D) - (I)
• (A) - (III), (B) - (I), (C) - (IV), (D) - (II)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

Remember that humus is organic matter, so Carbon is its backbone and most abundant element (over 50%). Oxygen is the next most abundant. Hydrogen and Nitrogen are present in much smaller percentages. This hierarchy helps in solving matching questions.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question asks to match the primary elemental components of humus (stable organic matter in soil) with their approximate percentage content.

Step 3: Detailed Explanation:
The elemental composition of humus can vary, but a typical approximation is as follows:
\[\begin{array}{rl} \bullet & \text{(A) Carbon (C): This is the main component of all organic matter. In humus, it typically ranges from 55-60%. So, (A) matches (III).} \\ \bullet & \text{(B) Oxygen (O): Oxygen is another major component, typically making up around 35-40%. So, (B) matches (I).} \\ \bullet & \text{(C) Hydrogen (H): Hydrogen is present in smaller amounts, usually around ~5%. So, (C) matches (II).} \\ \bullet & \text{(D) Nitrogen (N): Nitrogen content is also relatively small, but crucial for soil fertility. There seems to be a mismatch in the provided options as nitrogen is typically around 3-6%, similar to hydrogen. Given the choices, 15% (IV) is a possible, though high, value provided in some contexts, making it the only remaining match for Nitrogen. So, (D) matches (IV).} \\ \end{array}\] The most consistent matching based on the dominant elements is A-III, B-I, C-II, D-IV.

Step 4: Final Answer:
The correct matching option is (A) - (III), (B) - (I), (C) - (II), (D) - (IV).