Which of the following does not have abnormal electronic configuration ?

Options

A. Cr
B. Pd
C. Pt
D. Hg

Answer

To determine which of the following elements does not have an abnormal electronic configuration, we will analyze the electronic configurations of the given elements one by one.

### Step 1: Understanding Abnormal Electronic Configuration
Abnormal electronic configurations occur when the actual electron configuration of an element deviates from what would be expected based on the Aufbau principle. This often happens in transition metals where stability is achieved through half-filled or fully filled d-orbitals.

### Step 2: Analyzing Each Option

**Option 1: Chromium (Cr)**
- Expected electronic configuration: Argon 3d⁴ 4s²
- Actual electronic configuration: Argon 3d⁵ 4s¹
- Explanation: Chromium has an abnormal electronic configuration because it prefers to have a half-filled d-subshell (3d⁵), which is more stable than the expected configuration.

**Option 2: Palladium (Pd)**
- Expected electronic configuration: Argon 4s² 3d¹⁰ 4p⁶ 4d⁸
- Actual electronic configuration: Krypton 4d¹⁰
- Explanation: Palladium has an abnormal electronic configuration because it has a fully filled d-subshell (4d¹⁰), which is more stable than the expected configuration.

**Option 3: Platinum (Pt)**
- Expected electronic configuration: Xenon 4f¹⁴ 5d¹⁰ 6s² or Xenon 4f¹⁴ 5d⁸ 6s²
- Actual electronic configuration: Xenon 4f¹⁴ 5d⁹ 6s¹
- Explanation: Platinum also has an abnormal electronic configuration as it prefers to have a stable arrangement with a half-filled d-subshell.

**Option 4: Mercury (Hg)**
- Expected electronic configuration: Xenon 4f¹⁴ 5d¹⁰ 6s²
- Actual electronic configuration: Xenon 4f¹⁴ 5d¹⁰ 6s²
- Explanation: Mercury has a normal electronic configuration as it follows the expected filling order without any deviation.

### Conclusion
Among the options analyzed, **Mercury (Hg)** does not have an abnormal electronic configuration. Therefore, the correct answer is:

**Answer: Mercury (Hg)**