Free Electronic Configuration MCQs with Answers
103 Electronic Configuration MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Electronic configuration describes how electrons occupy shells, subshells and orbitals around an atom. Questions use the Aufbau principle, Pauli exclusion principle and Hund's rule to write configurations, identify valence electrons, form ions and explain periodic trends, including common exceptions such as chromium and copper.
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103 questions · page 3 of 6
- A. tritium
- B. deuterium
- C. protium
- D. ortho-hydrogen
Explanation: Tritium is hydrogen-3, containing one proton and two neutrons, and it is radioactive.
Correct answer: tritium- A. [Ar] 3d4 4s2
- B. [Ar] 3d5 4s1
- C. [Ar] 3d6 4s1
- D. [Ar] 3d1 4s2
Explanation: It is [Ar] 3d⁵ 4s¹This happens in Cr, as one 4s electron moves to the 3d sublevel. But why?
Correct answer: [Ar] 3d5 4s1- A. 3
- B. 2
- C. 1
- D. 4
Explanation: Boron (B) has an atomic number of 5. In the L shell, the 2s subshell can hold a maximum of 2 electrons, and the 2p subshell can hold a…
Correct answer: 3- A. 3s, 3p
- B. 4s, 3d
- C. 3s, 3d
- D. 4s, 3p
Explanation: The full electronic configuration in order of increasing energy is as follows: 1s2, 2s2, 2p6, 3s2, 3p6, 4s1 The correct option according…
Correct answer: 4s, 3p- A. Sr2+
- B. Kr
- C. Se4+
- D. Br-1
Explanation: Isoelectronic species have the same number of electrons. Sr2+ (36 electrons), Kr (36 electrons), and Br- (36 electrons) all have 36…
Correct answer: Se4+- A. 2
- B. 14
- C. 10
- D. 6
Explanation: p subshell has 3 orbit and 1 orbit has maximum 2 electrons.
Correct answer: 6- A. Ground state
- B. Excited state
- C. Hybridized state
- D. Molecular state
Explanation: This configuration represents ground state electronic configuration of nitrogen atom
Correct answer: Ground state- A. Sr³⁸
- B. Tc43
- C. Ru¹⁰¹
- D. Pd⁴⁶
Explanation: Calculate the total number of electrons: 36 (from Kr) + 2 + 5 = 43 electrons.
Correct answer: Tc43- A. 3p
- B. 3d
- C. 3f
- D. 4s
Explanation: After the 3s sub-shell, the next sub-shell to fill would be the 3p sub-shell.
Correct answer: 3p- A. High-energy electron beam
- B. X-rays
- C. Alpha particles
- D. All of the above
Explanation: Molecular ions are formed by passing high-energy electron beams, X-rays, or alpha particles through gases.
Correct answer: All of the above- A. 1s2, 2s2, 2p2
- B. 1s2, 2s2, 2px1, 2py1
- C. 1s2, 2s2, 2px2
- D. 1s2, 2s1, 2px1, 2py1, 2pz1
Explanation: In the excited state of carbon, electrons absorb energy and are promoted to higher energy orbitals, which results in a different…
Correct answer: 1s2, 2s1, 2px1, 2py1, 2pz1- A. 23, [Ar] 3d⁶
- B. 24, [Ar] 4s² 3d⁴
- C. 24, [Ar] 4s¹ 3d⁵
- D. 25, [Ar] 4s² 3d⁴
Explanation: The stable ion of the element X is tri positive, meaning it has lost three electrons.
Correct answer: 24, [Ar] 4s¹ 3d⁵- A. [He]2s1
- B. [Ne] 3s1
- C. [Ne]3s2
- D. [He]2s2
Explanation: The correct electronic configuration for sodium-11 is [Ne] 3s1. Sodium has 11 electrons, and its configuration follows that of the noble…
Correct answer: [Ne] 3s1- A. 1s¹ 2s¹ 2p¹
- B. 2s¹ 2p²
- C. 3p³
- D. 4s² 4p¹
Explanation: The correct answer is 4s² 4p¹, which corresponds to gallium (Ga), a Group III element.
Correct answer: 4s² 4p¹- A. 1s2 2s2 2p6 3s2 3p6 3d10 4s2
- B. 1s2 2s2 2p6 3s2 3p6 3d10
- C. 1s2 2s2 2p6 3s2 3p6 3d9 4s2
- D. 1s2 2s2 2p6 3s2 3p5 3d10 4s2
Explanation: The electron configuration of neutral gallium (Ga) is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1.
Correct answer: 1s2 2s2 2p6 3s2 3p6 3d10- A. Hund's Rule
- B. Pauli's exclusion principle
- C. Aufbau's principle
- D. Heisenberg's principle
Explanation: The explanation for this question will be added soon.
Correct answer: Hund's Rule- A. N+1 rule
- B. Aufbau's principle
- C. Hund's rule
- D. It is not filled before 3d
Explanation: The explanation for this question will be added soon.
Correct answer: N+1 rule- A. 2
- B. 6
- C. 10
- D. 14
Explanation: Each p subshell holds at most 6 electrons.
Correct answer: 6- A. 4s
- B. 2p
- C. 2d
- D. 3s
Explanation: The orbital energies are compared with the help of n+l rule. The higher value of n+l, higher is the energy of the orbital.
Correct answer: 4s- A. Aufbau Principle
- B. n+I Rule
- C. Hund's Rule
- D. Pauli's Exclusion Principle
Explanation: According to Hund's rule every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and…
Correct answer: Hund's Rule