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 determine which electronic configurations belong to main group elements, we need to examine the positions of these elements in the periodic table. Main group elements are those found in the s- and p-blocks.
- A. [Ne]3s\(^1\): This configuration corresponds to an element in the alkali metal group (main group element).
Thus, A is correct.
- B. [Ar]3d\(^3\)4s\(^2\): This configuration corresponds to an element in the d-block (transition metal), not a main group element.
Thus, B is incorrect.
- C. [Kr]4d\(^5\)3s\(^2\)5p\(^5\): This configuration corresponds to an element in the p-block (halogen).
Thus, C is correct.
- D. [Ar]3d\(^10\)4s\(^1\): This configuration corresponds to an element in the d-block (transition metal), but it involves the 4s orbital, which is characteristic of main group elements.
Thus, D is correct.
- E. [Rn]5f\(^7\)6d\(^2\)7s\(^2\): This configuration corresponds to an element in the f-block (lanthanide series), not a main group element.
Thus, E is incorrect.

Thus, the correct answer is (3) A, C, and D only.