For the correct assignment of electronic configuration of a complex, the valence bond theory often requires the measurement of

Options

A. molar conductance
B. optical activity
C. magnetic moment
D. dipole moment

Answer

To solve the question regarding the correct assignment of electronic configuration of a complex using valence bond theory, we will analyze each option provided and determine which one is most relevant.

### Step-by-Step Solution:

1. **Understanding Valence Bond Theory**:
- Valence bond theory (VBT) is used to explain the bonding in coordination complexes by considering the hybridization of metal orbitals and the pairing of electrons.

2. **Analyzing the Options**:
- **Option 1: Molar Conductance**:
- Molar conductance measures the ability of a solution to conduct electricity. It is not directly related to the electronic configuration of a complex.
- **Option 2: Optical Activity**:
- Optical activity refers to the ability of a compound to rotate plane-polarized light. While it can indicate chirality, it does not provide direct information about the electronic configuration.
- **Option 3: Magnetic Moment**:
- The magnetic moment is a measure of the magnetic properties of a complex, which is directly related to the number of unpaired electrons present in the complex. The formula for calculating magnetic moment is \( \mu = \sqrt{n(n + 2)} \), where \( n \) is the number of unpaired electrons. This is crucial for determining the electronic configuration.
- **Option 4: Dipole Moment**:
- Dipole moment measures the polarity of a molecule. While it can provide information about molecular geometry, it does not directly relate to the electronic configuration.

3. **Conclusion**:
- Among the options analyzed, the magnetic moment is the most relevant measurement for the correct assignment of electronic configuration of a complex using valence bond theory. Therefore, the correct answer is **Option 3: Magnetic Moment**.

### Final Answer:
The valence bond theory often requires the measurement of **magnetic moment** for the correct assignment of electronic configuration of a complex.

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