Which one of the following represent a d-block

Options

A. `[Rn] 6d^10 7s^2 7p^2`
B. `[Xe] 4f^1 5d^7 6s^2`
C. `[Xe] 4f^14 5d^1 6s^2`
D. `[Xe] 5d^8 6s^2`

Explanation

To determine which of the given options represents a d-block element, we need to analyze the electronic configurations of the options provided. Here’s a step-by-step solution:

### Step 1: Understand the d-block Elements
- d-block elements are characterized by the presence of electrons in the d subshell. The general electronic configuration for d-block elements can be expressed as:
\[ \text{[Noble gas]} \, ns^2 \, (n-1)d^{1-10} \]
where \( n \) is the principal quantum number.

### Step 2: Analyze Each Option
- We need to check the electronic configurations of the options provided to identify which one fits the d-block configuration.

### Step 3: Evaluate Option 1
- If the electronic configuration shows electrons filling the p orbital (e.g., \( ns^2 \, np^{1-6} \)), it indicates a p-block element. Therefore, Option 1 is not a d-block element.

### Step 4: Evaluate Option 2
- If the configuration involves f orbitals (e.g., \( (n-2)f^{1-14} \)), it indicates an f-block element. Since the d subshell is not being filled, Option 2 is also not a d-block element.

### Step 5: Evaluate Option 3
- Similar to Option 2, if the configuration involves f orbitals, it indicates an f-block element. Therefore, Option 3 is not a d-block element.

### Step 6: Evaluate Option 4
- If the configuration is of the form \( [\text{Noble gas}] \, ns^2 \, (n-1)d^{1-10} \), it indicates that the d subshell is being filled. This matches the definition of a d-block element. Therefore, Option 4 is a d-block element.

### Conclusion
- The correct answer is **Option 4**, as it satisfies the general electronic configuration of d-block elements.

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