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 5 of 6
- A. Ar & Cl-
- B. Ca & Ar
- C. Mg and Na
- D. Ag & Sn
Explanation: Argon has 18 electrons. The chloride ion also has 18 electrons.
Correct answer: Ar & Cl-- A. 37
- B. 32
- C. 35
- D. 20
Explanation: Atom A has 18 electrons with net charge of -1 which means it gained one electron.
Correct answer: 37- A. Ar & Cl-1
- B. Ca & Ar
- C. Mg & Na
- D. Ag & Sn
Explanation: Ar = 1s22s22p63s23p6 Cl- = 1s22s22p63s23p6 (doing for 18 electron instead of 17 because it gained one electron/anion)
Correct answer: Ar & Cl-1- A. Charge number
- B. Mass number
- C. Atomic number
- D. Magic number
Explanation: Mass number is the sum of protons and neutrons in the nucleus.
Correct answer: Mass number- A. 3d10 4s1
- B. 3d11 4s0
- C. 3d10 4s2
- D. 3d10 4s0
Explanation: The electronic configuration of copper (Cu) is obtained by filling the orbitals in order of increasing energy.
Correct answer: 3d10 4s1- A. diamagnetic
- B. paramagnetic
- C. ferromagnetic
- D. electromagnetic
Explanation: Those substances which have at least only one unpaired electron are called diamagnetic substances.
Correct answer: paramagnetic- A. The number of electrons in the outermost shell
- B. The number of electrons that are easily ejected
- C. The number of unpaired electrons
- D. The number of lone pair electrons
Explanation: A paramagnetic substance is one that is weakly attracted by a magnetic field due to the presence of unpaired electrons in its atoms or…
Correct answer: The number of unpaired electrons- A. N
- B. P-³
- C. K+
- D. F-
Explanation: O2-, F-, Na+ and Mg2+ are known as isoelectronic species as they all have the same no. of electrons(10).
Correct answer: F-- A. Hund's rule
- B. Aulban rule
- C. Paoli's exclusion lrinciple
- D. Thumb rule
Explanation: Hund's Rule: Hund's rule is a principle in quantum mechanics that states that for a given electron shell, orbitals of equal energy are…
Correct answer: Hund's rule- A. Protons
- B. Neutrons
- C. Electrons
- D. All of above
Explanation: Electrons (especially valence electrons) are only subatomic particles which are involved in ordinary chemical changes
Correct answer: Electrons- A. Proton
- B. Electron
- C. Neutrons
- D. None of above
Explanation: Therefore, the correct option is "None of the above" as H+ ion and helium atom have different numbers of protons, electrons, and neutrons.
Correct answer: None of above- A. Diamagnetic
- B. Paramagnetic
- C. Ferromagnetic
- D. Anti Ferromagnetic
Explanation: Paramagnetic: Oxygen molecules (O2) are paramagnetic. Paramagnetic substances have unpaired electrons, which generate a net magnetic…
Correct answer: Paramagnetic- A. Coulomb potential
- B. Vapor pressure
- C. Electronic configuration
- D. Entropy
Explanation: The Aruba principle, also known as the Aufbau principle, governs the filling order of atomic orbitals in an atom's electronic…
Correct answer: Electronic configuration- A. 1s22s22p63s23p63d3
- B. 1s22s22p63s23p63d14s2
- C. 1s22s22p63s23p63d34s2
- D. 1s22s22p63s23p63d34p1
Explanation: The electronic configuration of an atom is determined by the Aufbau Principle, which states that electrons fill the lowest energy orbitals…
Correct answer: 1s22s22p63s23p63d14s2- A. -2
- B. -1
- C. +2
- D. +1
Explanation: The element with atomic number 19 is potassium (K) which is a group 1 metal. Hence it loses one electron to form the ion valence of K+1.
Correct answer: +1- A. N2
- B. O2
- C. F2
- D. He22+
Explanation: The correct answer is O2. According to molecular orbital theory, O2 has a configuration with two unpaired electrons in the π* 2p molecular…
Correct answer: O2- A. N2-
- B. Cl2-
- C. H2+
- D. O2
Explanation: To determine if a molecule has unpaired electrons in antibonding molecular orbitals, examine the molecular orbital diagrams.
Correct answer: H2+- A. [Ar] 4S2 3d4
- B. [Ar] 4S0 3d10
- C. [Ar] 4S1 3d10
- D. [Ar] 4S2 3d7 4p2
Explanation: It is a transition element. Copper (Cu) is a chemical element, a reddish, extremely ductile metal of Group 11 (IB) of the periodic table…
Correct answer: [Ar] 4S1 3d10- A. Option A
- B. Option B
- C. Option C
- D. Both option B and C are correct
Explanation: Options A and D are incorrect because two electrons with the same spin are not added to the same orbitals.
Correct answer: Both option B and C are correct- A. I only
- B. I and III only
- C. I and II only
- D. II and III only
Explanation: The electron configuration for sodium (23Na) is correctly given as 1s22s22p63s1.
Correct answer: I and II only