Which of the following metals have both valence shell and penultimate shell partially filled ?

Options

A. Cr
B. Mo
C. Cu
D. Zn

Answer

To determine which metals have both their valence shell and penultimate shell partially filled, we will analyze the electronic configurations of the given metals.

### Step-by-Step Solution:

1. **Identify the Valence and Penultimate Shells**:
- The valence shell is the outermost shell of an atom, while the penultimate shell is the shell just before the valence shell. If the valence shell is designated as 'n', then the penultimate shell is 'n-1'.

2. **Analyze the Electronic Configuration of Each Metal**:
- **Chromium (Cr)**:
- Electronic Configuration: Argon (Ar) 3d⁵ 4s¹
- Valence Shell (4s): Partially filled (1 electron).
- Penultimate Shell (3d): Partially filled (5 electrons).
- Conclusion: Both shells are partially filled.

- **Molybdenum (Mo)**:
- Electronic Configuration: Krypton (Kr) 4d⁵ 5s¹
- Valence Shell (5s): Partially filled (1 electron).
- Penultimate Shell (4d): Partially filled (5 electrons).
- Conclusion: Both shells are partially filled.

- **Copper (Cu)**:
- Electronic Configuration: Argon (Ar) 3d¹⁰ 4s¹
- Valence Shell (4s): Partially filled (1 electron).
- Penultimate Shell (3d): Completely filled (10 electrons).
- Conclusion: One shell is partially filled, and the other is completely filled.

- **Zinc (Zn)**:
- Electronic Configuration: Argon (Ar) 3d¹⁰ 4s²
- Valence Shell (4s): Completely filled (2 electrons).
- Penultimate Shell (3d): Completely filled (10 electrons).
- Conclusion: Both shells are completely filled.

3. **Summarize the Findings**:
- From the analysis, we find that:
- **Chromium (Cr)**: Both shells partially filled.
- **Molybdenum (Mo)**: Both shells partially filled.
- **Copper (Cu)**: One shell partially filled, one completely filled.
- **Zinc (Zn)**: Both shells completely filled.

4. **Final Answer**:
- The metals that have both their valence shell and penultimate shell partially filled are **Chromium (Cr)** and **Molybdenum (Mo)**.