The correct statement among I to III are:
(I) Valence bond theory cannot explain the color exhibited by transition metal complexes
(II) Valence bond theory can predict quantitatively the magnetic properties of transition metal complexes
(III) Valence bond theory cannot distinguish ligands as weak and strong field ones

Options

A. (I),(II) and (III)
B. (I) and (II) only
C. (I) and (III) only
D. (II) and (III) only

Explanation

To solve the question regarding the statements about valence bond theory (VBT) and its relation to transition metal complexes, we will analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** Valence bond theory cannot explain the color exhibited by transition metal complexes.

- **Explanation:** The color of transition metal complexes arises from electronic transitions between d-orbitals, which are influenced by the ligand field. Valence bond theory does not account for these transitions and therefore cannot explain the color. Instead, crystal field theory (CFT) is used to explain the color of these complexes.

**Conclusion:** Statement I is correct.

**Hint:** Consider how electronic transitions in d-orbitals relate to color and which theory addresses this.

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### Step 2: Analyze Statement II
**Statement II:** Valence bond theory can predict quantitatively the magnetic properties of transition metal complexes.

- **Explanation:** While VBT can qualitatively describe the magnetic properties based on the number of unpaired electrons, it does not provide a quantitative prediction. The quantitative prediction of magnetic properties is better handled by other theories, such as crystal field theory or ligand field theory.

**Conclusion:** Statement II is incorrect.

**Hint:** Think about the difference between qualitative and quantitative predictions in the context of magnetic properties.

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### Step 3: Analyze Statement III
**Statement III:** Valence bond theory cannot distinguish ligands as weak and strong field ones.

- **Explanation:** The distinction between weak field and strong field ligands is based on the spectrochemical series, which is derived from experimental observations. Valence bond theory does not incorporate this concept and thus cannot distinguish between these types of ligands.

**Conclusion:** Statement III is correct.

**Hint:** Recall how the spectrochemical series is used to classify ligands and the limitations of VBT in this context.

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### Final Conclusion
Based on the analysis:
- Statement I is correct.
- Statement II is incorrect.
- Statement III is correct.

Thus, the correct statements are I and III.

### Answer
The correct option is C (I and III are correct).

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