COMEDK2025Chemistryd and f Block ElementsActual
Choose the correct metal/ ion from the brackets which .......... A. has chemical reactivity similar to that of the first few members of the Lanthanoids ( Zn , Ca , Fe , Cu ) . B. has stable 4 f ^7 electronic configuration, but acts as a strong reducing agent and converts to M ³⁺ state. ( Eu ²⁺, Ce ²⁺, Pr ²⁺, Dy ²⁺ ) C. is a colorless ion ( Tm ³⁺, Lu ³⁺, Gd ³⁺, Sm ³⁺ ) . D. shows stable +2 oxidation state and is diama
Options
- AA : Zn B : Ce ²⁺, C : Gd ³⁺ D : Sm
- BA : Ca B : Eu ²⁺ C : Lu ³⁺ D : ~ Yb
- CA : Fe B : Pr ²⁺ C : Tm ³⁺ D : ~ Ce
- DA : Cu B : Dy ²⁺ C : Sm ³⁺ D : ~ Ho
Correct answer
B. A : Ca B : Eu ²⁺ C : Lu ³⁺ D : ~ Yb
Step-by-step solution
A. The lanthanoids are highly reactive metals, similar to calcium. Among the choices, calcium (Ca) exhibits chemical reactivity comparable to the early lanthanoids. B. Europium (Eu) has the electronic configuration [Xe] 4f^7 6s^2 . The ion Eu ²⁺ has a stable half-filled 4f^7 configuration. However, it is a strong reducing agent because it readily loses an electron to form the more stable Eu ³⁺ state ( 4f^6 ). C. Lu ³⁺ has the electronic configuration [Xe] 4f¹⁴ . Since the 4f subshell is completely filled, there are