The electron which take part in order to exhibit variable oxidation states by transition metals are

Options

A. ns only
B. (n-1)d only
C. ns and (n-1)d only but not np
D. (n-1)d and np only but not ns

Answer

To solve the question regarding which electrons participate in exhibiting variable oxidation states by transition metals, we can follow these steps:

### Step 1: Understand the electronic configuration of transition metals
Transition metals are defined as d-block elements, which have an electronic configuration that includes d-orbitals. The general electronic configuration for these elements is given by:
\[ \text{(n-1)d}^{1-10} \text{ns}^{1-2} \]
where \( n \) is the principal quantum number.

### Step 2: Identify the relevant orbitals
In transition metals, the relevant orbitals that can participate in bonding and oxidation state changes are:
- The \( ns \) orbital (the outermost s-orbital)
- The \( (n-1)d \) orbitals (the d-orbitals that are one principal quantum number lower than the outermost shell)

### Step 3: Exclude the np orbitals
Transition metals do not utilize the \( np \) orbitals for exhibiting variable oxidation states. This is because the \( np \) orbitals are typically involved in the chemistry of main group elements rather than transition metals.

### Step 4: Conclusion
Based on the above points, the electrons that participate in exhibiting variable oxidation states in transition metals are:
- \( ns \) electrons
- \( (n-1)d \) electrons

Thus, the correct answer to the question is that the electrons which take part in order to exhibit variable oxidation states by transition metals are \( ns \) and \( (n-1)d \) only, but not \( np \).

### Final Answer:
**The electrons which take part in order to exhibit variable oxidation states by transition metals are \( ns \) and \( (n-1)d \) only, but not \( np \).**

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