`{:(,"List-I",,"List-II",),((P),ZnO,(1),"Yellow when cold and brown on heating",),((Q),Bi_(2)O_(3),(2),"Blue when cold and white on heating",),((R),CoCI_(2).6H_(2)O,(3),"White when cold and yellow on heating",),((S),CuSO_(4)5H_(2)O,(4),"Pink when cold and blue on heating",):}`

Options

A. `{:(P,Q,R,S),(3,4,2,1):}`
B. `{:(P,Q,R,S),(1,1,3,4):}`
C. `{:(P,Q,R,S),(1,2,4,2):}`
D. `{:(P,Q,R,S),(3,1,3,2):}`

Answer

To solve the matching question, we need to correlate the compounds listed in List-I with their respective color changes described in List-II. Let's analyze each compound step by step.

### Step 1: Analyze ZnO (P)
- **Compound**: ZnO (Zinc Oxide)
- **Color when cold**: White
- **Color when heated**: Yellow
- **Reason**: When ZnO is heated, it shows a metal excess defect due to anion vacancy, leading to the formation of F centers, which gives it a yellow color.
- **Match**: ZnO matches with (3) "White when cold and yellow on heating".

### Step 2: Analyze Bi₂O₃ (Q)
- **Compound**: Bi₂O₃ (Bismuth Trioxide)
- **Color when cold**: Yellow
- **Color when heated**: Brown
- **Reason**: Bismuth trioxide is yellow at room temperature and turns brown upon heating due to the loss of oxygen and a stoichiometric defect.
- **Match**: Bi₂O₃ matches with (1) "Yellow when cold and brown on heating".

### Step 3: Analyze CoCl₂·6H₂O (R)
- **Compound**: CoCl₂·6H₂O (Cobalt(II) Chloride Hexahydrate)
- **Color when cold**: Pink
- **Color when heated**: Blue
- **Reason**: Cobalt(II) chloride is pink when hydrated and turns blue upon heating due to the loss of water of crystallization and formation of a tetrahedral complex.
- **Match**: CoCl₂·6H₂O matches with (4) "Pink when cold and blue on heating".

### Step 4: Analyze CuSO₄·5H₂O (S)
- **Compound**: CuSO₄·5H₂O (Copper(II) Sulfate Pentahydrate)
- **Color when cold**: Blue
- **Color when heated**: White
- **Reason**: Copper(II) sulfate is blue when hydrated and turns white upon heating due to the loss of water of crystallization.
- **Match**: CuSO₄·5H₂O matches with (2) "Blue when cold and white on heating".

### Final Matching
Now, we can summarize the matches:
- P (ZnO) → (3) "White when cold and yellow on heating"
- Q (Bi₂O₃) → (1) "Yellow when cold and brown on heating"
- R (CoCl₂·6H₂O) → (4) "Pink when cold and blue on heating"
- S (CuSO₄·5H₂O) → (2) "Blue when cold and white on heating"

### Conclusion
The correct option that matches all the compounds with their respective color changes is **Option 4**.

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