MCQEasyJEE 2024Electronic Configuration

JEE Chemistry 2024 Question with Solution

Match List-I with List-II:

List-I (Element) | List-II (Electronic Configuration)

A. N | I. [Ar] 3d10 4s2 4p5

B. S | II. [Ne] 3s2 3p4

C. Br | III. [He] 2s2 2p3

D. Kr | IV. [Ar] 3d10 4s2 4p6

  • A

    A-IV, B-III, C-II, D-I

  • B

    A-III, B-II, C-I, D-IV

  • C

    A-I, B-IV, C-III, D-II

  • D

    A-II, B-I, C-IV, D-III

Answer

Correct answer:B

Step-by-step solution

Standard Method

Given: Match the elements N, S, Br, and Kr with their electronic configurations.

Find: The correct correspondence between List-I and List-II.

Electronic configurations of the given elements are:

  • N : 1s22s22p31s^2 2s^2 2p^3, which is written as [He] 2s2 2p3.
  • S : [Ne]3s23p4[Ne] 3s^2 3p^4.
  • Br : [Ar]3d104s24p5[Ar] 3d^{10} 4s^2 4p^5.
  • Kr : [Ar]3d104s24p6[Ar] 3d^{10} 4s^2 4p^6.

Therefore, the matching is:

AIIIBIICIDIV\begin{aligned} A &\to III \\ B &\to II \\ C &\to I \\ D &\to IV \end{aligned}

So the correct matching is A-III, B-II, C-I, D-IV.

The correct option is B.

Element-wise Identification

Given: Four elements and four electronic configurations are listed.

Find: Which option gives the correct one-to-one match.

  1. For N with atomic number 77:
1s22s22p31s^2 2s^2 2p^3

This corresponds to [He] 2s2 2p3, so A \to III.

  1. For S with atomic number 1616:
[Ne]3s23p4[Ne] 3s^2 3p^4

So B \to II.

  1. For Br with atomic number 3535:
[Ar]3d104s24p5[Ar] 3d^{10} 4s^2 4p^5

So C \to I.

  1. For Kr with atomic number 3636:
[Ar]3d104s24p6[Ar] 3d^{10} 4s^2 4p^6

So D \to IV.

Hence,

(A)(III),(B)(II),(C)(I),(D)(IV)(A) - (III), \, (B) - (II), \, (C) - (I), \, (D) - (IV)

This matches Option (2).

Note: The provided the solution is unrelated to this question and discusses electronic effects in organic chemistry, so the answer is derived from the question content and the provided correct answer field instead.

Common mistakes

  • Confusing N with a third-period element is incorrect because nitrogen belongs to period 2. Use its atomic number 77 to write 1s22s22p31s^2 2s^2 2p^3, then match it with [He] 2s2 2p3.

  • Ignoring the completely filled 4p64p^6 subshell for Kr is wrong because krypton is a noble gas. Check that noble gases have filled valence shells, so Kr must match [Ar] 3d10 4s2 4p6.

  • Mixing up Br and Kr is a common error because both are in period 4. Bromine has one electron less than krypton, so Br is 4p54p^5 while Kr is 4p64p^6.

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