Question

Identify the element from following such that the last electron is placed in $(\text{n} - 1)\text{d}$ orbital.

• A. Dy
• B. Ag
• C. Pu
• D. Pa

Hint:

Transition metals = $d$-block; Lanthanides/Actinides = $f$-block.

Answer 1

The Correct Option is B

Step 1: Concept Elements where the last electron enters the $(n-1)d$ subshell are transition metals ($d$-block elements).

Step 2: Meaning Dy (Dysprosium), Pu (Plutonium), and Pa (Protactinium) are $f$-block elements where the last electron enters $(n-2)f$.

Step 3: Analysis Silver (Ag) is located in Group 11 and Period 5. Its electronic configuration ends in $4d^{10} 5s^1$.

Step 4: Conclusion Since the differentiating electron in Ag is in the $d$ orbital, it satisfies the condition. Final Answer: (B)