Configuration Electron and Quantum Number

Which of the following is the correct electron configuration for a neutral oxygen atom?

• 1s² 2s² 2p⁴

• 1s² 2s² 2p³

• 1s² 2s² 2p⁶

• 1s² 2s² 2p⁵

What is the maximum number of electrons that can occupy the third energy level (n = 3)?

• 2

• 8

• 18

• 32

Which of the following quantum numbers determines subshell?

• Principal quantum number (n)

• Azimuth momentum quantum number (l)

• Magnetic quantum number (m)

• Spin quantum number (s)

What is the correct order of filling orbitals according to the Aufbau principle from subshell method?

• 1s, 2s, 2p, 3s, 3p, 4s

• 1s, 2s, 2p, 3s, 3p, 4s

• 1s, 2p, 2s, 3s, 3p, 4s

• 1s, 2s, 3s, 3p, 4s, 4p

For an electron in the n = 4, l = 2 subshell, what are the possible values of the magnetic quantum number (m)?

• -2, -1, 0, +1, +2

• -1, 0, +1

• 0, +1, +2

• • -3, -2, -1, 0, +1, +2, +3

Which of the following represents a set of quantum numbers that is not possible?

• n = 3, l = 2, m = 1, s = +1/2

• n = 2, l = 1, m = 0, s = -1/2

• n = 3, l = 3, m = 0, s = +1/2

• n = 4, l = 0, m = 0, s = +1/2

The Pauli Exclusion Principle states that:

• Electrons fill the lowest energy orbitals first.

• No two electrons in an atom can have the same set of four quantum numbers.

• Electrons occupy orbitals singly before pairing up.

• The maximum number of electrons in an orbital is two.

How many unpaired electrons are present in the ground state of a nitrogen atom?

• 0

• 1

• 2

• 3

The electron configuration of chromium (atomic number Cr = 24 ) is an exception to the Aufbau principle. What is its actual electron configuration?

• [Ar] 4s² 3d⁴

• [Ar] 4s¹ 3d⁵

• [Ar] 4s⁰ 3d⁶

• [Ar] 4s² 3d³

What is the electron configuration of a Cu²⁺ (atomic number Cu = 29) ion?

• [Ar] 3d⁹

• [Ar] 4s² 3d⁷

• [Ar] 3d¹⁰

• [Ar] 3d⁸