Which of the following has the same number of electrons in its outermost shell and penultimate shell ?

Options

A. Elements with atomic numbers 30,48,80
B. Elements with atomic number 14,15,16
C. Elements with atomic numbers 20,30,50
D. Elements with atomic number 10,18,26

Explanation

To solve the question "Which of the following has the same number of electrons in its outermost shell and penultimate shell?", we will analyze each option by determining the electronic configurations of the elements mentioned and comparing the number of electrons in their outermost and penultimate shells.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- The **outermost shell** (valence shell) is the shell with the highest principal quantum number (n).
- The **penultimate shell** is the shell just before the outermost shell (n-1).

2. **Identifying the Options**:
- The options given are:
- A) Elements with atomic numbers 30, 48, 80
- B) Elements with atomic numbers 14, 15, 16
- C) Elements with atomic numbers 20, 30, 50
- D) Elements with atomic numbers 10, 18, 26

3. **Analyzing Each Option**:

**Option A: Atomic Numbers 30, 48, 80**
- Atomic number 30 (Zinc):
- Electronic configuration: [Ar] 4s² 3d¹⁰
- Outermost shell (n=4): 2 electrons (4s²)
- Penultimate shell (n-1=3): 10 electrons (3d¹⁰)
- Atomic number 48 (Cadmium):
- Electronic configuration: [Kr] 5s² 4d¹⁰
- Outermost shell (n=5): 2 electrons (5s²)
- Penultimate shell (n-1=4): 10 electrons (4d¹⁰)
- Atomic number 80 (Mercury):
- Electronic configuration: [Xe] 6s² 4f¹⁴ 5d¹⁰
- Outermost shell (n=6): 2 electrons (6s²)
- Penultimate shell (n-1=5): 14 electrons (5d¹⁰)
- **Conclusion for Option A**: No match.

**Option B: Atomic Numbers 14, 15, 16**
- Atomic number 14 (Silicon):
- Electronic configuration: [Ne] 3s² 3p²
- Outermost shell (n=3): 4 electrons (3s² 3p²)
- Penultimate shell (n-1=2): 10 electrons (2s² 2p⁶)
- Atomic number 15 (Phosphorus):
- Electronic configuration: [Ne] 3s² 3p³
- Outermost shell (n=3): 5 electrons (3s² 3p³)
- Penultimate shell (n-1=2): 10 electrons (2s² 2p⁶)
- Atomic number 16 (Sulfur):
- Electronic configuration: [Ne] 3s² 3p⁴
- Outermost shell (n=3): 6 electrons (3s² 3p⁴)
- Penultimate shell (n-1=2): 10 electrons (2s² 2p⁶)
- **Conclusion for Option B**: No match.

**Option C: Atomic Numbers 20, 30, 50**
- Atomic number 20 (Calcium):
- Electronic configuration: [Ar] 4s²
- Outermost shell (n=4): 2 electrons (4s²)
- Penultimate shell (n-1=3): 8 electrons (3s² 3p⁶)
- Atomic number 30 (Zinc): Already analyzed.
- Atomic number 50 (Tin):
- Electronic configuration: [Kr] 5s² 4d¹⁰ 5p²
- Outermost shell (n=5): 4 electrons (5s² 5p²)
- Penultimate shell (n-1=4): 10 electrons (4d¹⁰)
- **Conclusion for Option C**: No match.

**Option D: Atomic Numbers 10, 18, 26**
- Atomic number 10 (Neon):
- Electronic configuration: 1s² 2s² 2p⁶
- Outermost shell (n=2): 8 electrons (2s² 2p⁶)
- Penultimate shell (n-1=1): 2 electrons (1s²)
- Atomic number 18 (Argon):
- Electronic configuration: [Ne] 3s² 3p⁶
- Outermost shell (n=3): 8 electrons (3s² 3p⁶)
- Penultimate shell (n-1=2): 10 electrons (2s² 2p⁶)
- Atomic number 26 (Iron):
- Electronic configuration: [Ar] 4s² 3d⁶
- Outermost shell (n=4): 8 electrons (4s² 3d⁶)
- Penultimate shell (n-1=3): 10 electrons (3s² 3p⁶)
- **Conclusion for Option D**: No match.

4. **Final Answer**:
- After analyzing all options, none of the provided options have the same number of electrons in their outermost shell and penultimate shell.