Q131 / 200 · MHT CET - Medical 2026 (23 April Shift 1) · Chemistry
Identify the Lanthanoid ions having half filled and completely filled 4f orbitals respectively.
- A$\text{Eu}^{2+}$ and $\text{Tm}^{2+}$
- B$\text{Sm}^{2+}$ and $\text{Tm}^{3+}$
- Correct answerC$\text{Tb}^{4+}$ and $\text{Yb}^{2+}$
- D$\text{Dy}^{3+}$ and $\text{Yb}^{3+}$
Solution
The atomic number of Terbium (Tb) is $65$. Its electronic configuration is $[\text{Xe}] 4f^{9} 6s^{2}$.
For $\text{Tb}^{4+}$, four electrons are removed (two from $6s$ and two from $4f$), giving the configuration $[\text{Xe}] 4f^{7}$. This represents a half-filled $4f$ subshell.
The atomic number of Ytterbium (Yb) is $70$. Its electronic configuration is $[\text{Xe}] 4f^{14} 6s^{2}$.
For $\text{Yb}^{2+}$, two electrons are removed from the $6s$ orbital, giving the configuration $[\text{Xe}] 4f^{14}$. This represents a completely filled $4f$ subshell.
Thus, $\text{Tb}^{4+}$ and $\text{Yb}^{2+}$ have half-filled and completely filled $4f$ orbitals respectively.
Answer: $\text{Tb}^{4+}$ and $\text{Yb}^{2+}$
For $\text{Tb}^{4+}$, four electrons are removed (two from $6s$ and two from $4f$), giving the configuration $[\text{Xe}] 4f^{7}$. This represents a half-filled $4f$ subshell.
The atomic number of Ytterbium (Yb) is $70$. Its electronic configuration is $[\text{Xe}] 4f^{14} 6s^{2}$.
For $\text{Yb}^{2+}$, two electrons are removed from the $6s$ orbital, giving the configuration $[\text{Xe}] 4f^{14}$. This represents a completely filled $4f$ subshell.
Thus, $\text{Tb}^{4+}$ and $\text{Yb}^{2+}$ have half-filled and completely filled $4f$ orbitals respectively.
Answer: $\text{Tb}^{4+}$ and $\text{Yb}^{2+}$
Hence, the correct answer is option: 'C'.