`{:(" List-I"," List-II"),((P) "Four carbon atoms" ,(1) "Prop"),( (Q) "Three carbon atoms", (2) "Pent"),( (R ) "Five carbon atoms", (3) "But"),( (S) "Six carbon atoms", (4) "Hex"):}`

Options

A. P-3, Q-1, R-2, S-4
B. P-4, Q-2, R-1, S-3
C. P-1, Q-2, R-3, S-4
D. P-2, Q-4, R-1, S-3

Answer

To solve the question, we need to match the number of carbon atoms from List-I with the corresponding prefixes from List-II. Let's break it down step by step.

### Step-by-Step Solution:

1. **Identify the number of carbon atoms and their corresponding prefixes:**
- For 1 carbon atom, the prefix is **Meth**.
- For 2 carbon atoms, the prefix is **Eth**.
- For 3 carbon atoms, the prefix is **Pro**.
- For 4 carbon atoms, the prefix is **But**.
- For 5 carbon atoms, the prefix is **Pent**.
- For 6 carbon atoms, the prefix is **Hex**.

2. **Match each item from List-I with List-II:**
- **(P) Four carbon atoms**: The prefix for 4 carbon atoms is **But** (which corresponds to 3).
- **(Q) Three carbon atoms**: The prefix for 3 carbon atoms is **Pro** (which corresponds to 1).
- **(R) Five carbon atoms**: The prefix for 5 carbon atoms is **Pent** (which corresponds to 2).
- **(S) Six carbon atoms**: The prefix for 6 carbon atoms is **Hex** (which corresponds to 4).

3. **Compile the matches:**
- P (4 carbon atoms) matches with 3 (But).
- Q (3 carbon atoms) matches with 1 (Pro).
- R (5 carbon atoms) matches with 2 (Pent).
- S (6 carbon atoms) matches with 4 (Hex).

4. **Write the final matching:**
- P → 3
- Q → 1
- R → 2
- S → 4

5. **Conclusion:**
The correct matching is PQRS = 3124.

### Final Answer:
The correct option is **A: 3124**.