Question

Which among the following electronic configurations belong to main group elements?
A. [Ne]3s$^1$
B. [Ar]3d$^3$4s$^2$
C. [Kr]4d$^5$3s$^2$5p$^5$
D. [Ar]3d$^10$4s$^1$
E. [Rn]5f$^7$6d$^2$7s$^2$
Choose the correct answer from the options given below:

• A. A and C only
• B. D and E only
• C. A, C, and D only
• D. B and E only

Hint:

Main group elements are found in the s- and p-blocks of the periodic table. Transition metals and lanthanides belong to the d- and f-blocks.

Answer 1

The Correct Option is C

To classify electronic configurations as belonging to main group elements, their positions within the s- and p-blocks of the periodic table must be ascertained. Main group elements reside in these blocks.
- A. [Ne]3s\(^1\): This configuration is indicative of an alkali metal, a main group element. Therefore, A is correct.
- B. [Ar]3d\(^3\)4s\(^2\): This configuration represents a d-block element (transition metal), not a main group element. Consequently, B is incorrect.
- C. [Kr]4d\(^5\)3s\(^2\)5p\(^5\): This configuration corresponds to a p-block element (halogen). Hence, C is correct.
- D. [Ar]3d\(^10\)4s\(^1\): Although this configuration places the element in the d-block (transition metal), it includes the 4s orbital, a characteristic feature of main group elements. Therefore, D is correct.
- E. [Rn]5f\(^7\)6d\(^2\)7s\(^2\): This configuration signifies an f-block element (lanthanide series), not a main group element. Thus, E is incorrect.

Accordingly, the correct selections are A, C, and D solely.