Which among the following electronic configurations belong to main group elements? (A) [Ne]3s^1, (B) [Ar]3d^34s^2, (C) [Kr]4d^105…

Question

Which among the following electronic configurations belong to main group elements? (A) [Ne]3s^1, (B) [Ar]3d^34s^2, (C) [Kr]4d^105s^25p^5, (D) [Ar]3d^104s^1, (E) [Rn]5f^06d^27s^2.

Choose the correct answer from the option given below:

1. A. B and E only
2. B. A and C only (Correct answer)
3. C. D and E only
4. D. A, C and D only

Correct Answer

Option B — A and C only

Detailed Solution & Explanation

The correct answer is A and C only.

Key Points

• Main group (representative) elements have their outermost electron in an s- or p-orbital.
• (A) [Ne]3s$^1$ = Na (s-block, main group); (C) [Kr]4d$^{10}$5s$^2$5p$^5$ = I (p-block, main group).
• (B) [Ar]3d$^3$4s$^2$ = V and (D) [Ar]3d$^{10}$4s$^1$ = Cu are d-block; (E) [Rn]5f$^0$6d$^2$7s$^2$ = Th is f-block.
• Hence only A and C are main group elements.