Chemistry · Structure of Atom

JEE Main 2026 — 5 April, Morning Shift — Question 51

Identify the correct statements from the following : A. Heisenberg uncertainty principle is applicable to electron. B. The size of $2 p_{x}$ orbital is less than the size of $3 p_{x}$ orbital. C. The energy of 2s orbital of H atom is equal to the energy of 2s orbital of Li. D. The electronic configuration of Cr is $[\mathrm{Ar}] 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{1}$

Choose the correct answer from the options given below:

Option A:
A, B and C only
Option B:
A, B and D only
Correct
Option C:
B, C, and D only
Option D:
A, C and D only

Answer: B

Step-by-step solution

A) Heisenberg uncertainty principle is applicable to all the moving microscopic particles. (B) $2 p_{x}$ has less value of $n$ thus has lesser size than $3 \mathrm{p}_{\mathrm{x}}$ . (C) $\mathrm{E}_{2 \mathrm{~s}}(\mathrm{H}) \neq \mathrm{E}_{2 \mathrm{~s}}(\mathrm{Li})$ (D) $\mathrm{Cr}:-[\mathrm{Ar}] 3 \mathrm{~d}^{5} 4 \mathrm{~s}^{1}$

Correct statement are A, B and D.

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Exam: JEE Main 2026
Paper: 5 April, Morning Shift
Subject: Chemistry
Chapter: Structure of Atom
Topic: Electronic Configuration: Rules, Aufbau Principle and Exceptions

Arrange the following atomic orbitals of multi electron atoms in order of increasing energy. (A) n=3, ell=2, m=+1 (B) n=4, ell=0, m=0 (C)…

Answer: B

Step-by-step solution

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