chemistry : class11 f-Orbitals : Concept of orbitals : Structure of Atom MCQ Questions and Answers
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f-Orbitals
MCQ questions and answers.
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MCQ Questions
1. For an electron in an f-subshell, which complete set of possible values of the magnetic quantum number m_l is allowed?
A.
-3, -2, -1, 0, +1, +2, +3
B.
-2, -1, 0, +1, +2
C.
-4, -3, -2, -1, 0, +1, +2, +3, +4
D.
0, +1, +2, +3
Correct Answer:
-3, -2, -1, 0, +1, +2, +3
Explanation:
An f-subshell has azimuthal quantum number l = 3. Therefore, m_l can have all integral values from -l to +l, giving -3, -2, -1, 0, +1, +2, and +3.
2. How many orbitals are present in a single f-subshell, and what is the maximum number of electrons it can accommodate?
A.
5 orbitals and 10 electrons
B.
7 orbitals and 14 electrons
C.
9 orbitals and 18 electrons
D.
3 orbitals and 6 electrons
Correct Answer:
7 orbitals and 14 electrons
Explanation:
For an f-subshell, l = 3, so the number of orbitals is 2l + 1 = 7. Since each orbital can contain two electrons with opposite spins, the maximum capacity is 14 electrons.
3. An electron occupies a 4f orbital. What are the numbers of radial nodes and angular nodes associated with this orbital?
A.
3 radial nodes and 0 angular nodes
B.
0 radial nodes and 3 angular nodes
C.
1 radial node and 2 angular nodes
D.
2 radial nodes and 1 angular node
Correct Answer:
0 radial nodes and 3 angular nodes
Explanation:
For a 4f orbital, n = 4 and l = 3. The number of radial nodes is n - l - 1 = 4 - 3 - 1 = 0, while the number of angular nodes equals l = 3.
4. Which set of quantum numbers correctly represents an electron in a 5f orbital?
A.
n = 5, l = 3, m_l = -2, m_s = +1/2
B.
n = 5, l = 2, m_l = +3, m_s = -1/2
C.
n = 4, l = 3, m_l = +4, m_s = +1/2
D.
n = 5, l = 4, m_l = 0, m_s = -1/2
Correct Answer:
n = 5, l = 3, m_l = -2, m_s = +1/2
Explanation:
An f orbital requires l = 3, and for l = 3 the allowed m_l values range from -3 to +3. The principal quantum number n = 5 and spin quantum number m_s = +1/2 are also valid.
5. For a 6f orbital, which statement about its nodes is correct?
A.
It has 2 radial nodes and 3 angular nodes
B.
It has 3 radial nodes and 2 angular nodes
C.
It has 1 radial node and 5 angular nodes
D.
It has 4 radial nodes and 3 angular nodes
Correct Answer:
It has 2 radial nodes and 3 angular nodes
Explanation:
For a 6f orbital, n = 6 and l = 3. Radial nodes are n - l - 1 = 6 - 3 - 1 = 2, and angular nodes are l = 3.
6. Which conclusion follows directly from the value l = 3 for an f-orbital?
A.
The orbital has three angular nodes and seven possible orientations
B.
The orbital has three radial nodes and six possible orientations
C.
The orbital has seven angular nodes and three possible orientations
D.
The orbital has no angular nodes and seven possible orientations
Correct Answer:
The orbital has three angular nodes and seven possible orientations
Explanation:
The azimuthal quantum number l gives the number of angular nodes, so an f-orbital has three angular nodes. The number of possible m_l values is 2l + 1 = 7, corresponding to seven orientations.
7. Which of the following subshell descriptions is impossible for an f-subshell?
A.
4f with seven orbitals
B.
5f with fourteen electrons when completely filled
C.
3f with seven orbitals
D.
6f with magnetic quantum numbers ranging from -3 to +3
Correct Answer:
3f with seven orbitals
Explanation:
For a given principal quantum number n, l can range only from 0 to n - 1. Thus, for n = 3, the maximum l value is 2, so a 3f subshell with l = 3 cannot exist.
8. How many electrons in an f-subshell can have m_l = +2 and m_s = -1/2 at most?
A.
1
B.
2
C.
7
D.
14
Correct Answer:
1
Explanation:
The value m_l = +2 identifies one specific f orbital. That orbital can contain at most two electrons, but the specified spin m_s = -1/2 selects only one of them.
9. A completely filled 4f subshell contains electrons distributed among how many orbitals with each orbital having what spin arrangement?
A.
Seven orbitals, each containing two electrons with opposite spins
B.
Four orbitals, each containing three electrons with parallel spins
C.
Seven orbitals, each containing two electrons with parallel spins
D.
Fourteen orbitals, each containing one electron with alternating spins
Correct Answer:
Seven orbitals, each containing two electrons with opposite spins
Explanation:
An f-subshell has seven orbitals corresponding to its seven allowed m_l values. When completely filled, each orbital contains two electrons, and the Pauli exclusion principle requires their spins to be opposite.
10. For a 5f orbital, what is the total number of nodes, and how are they divided between radial and angular nodes?
A.
4 total nodes: 1 radial and 3 angular
B.
5 total nodes: 2 radial and 3 angular
C.
3 total nodes: 0 radial and 3 angular
D.
4 total nodes: 3 radial and 1 angular
Correct Answer:
4 total nodes: 1 radial and 3 angular
Explanation:
For 5f, n = 5 and l = 3. Radial nodes equal n - l - 1 = 1, angular nodes equal l = 3, and total nodes equal n - 1 = 4.
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