chemistry : class11 f-Subshell Characteristics : Concept of subshells : Structure of Atom MCQ Questions and Answers
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f-Subshell Characteristics
MCQ questions and answers.
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MCQ Questions
1. For an electron in an f-subshell, which complete set of quantum-number values is permissible?
A.
n = 4, l = 3, m_l = +3, m_s = -1/2
B.
n = 3, l = 3, m_l = 0, m_s = +1/2
C.
n = 4, l = 2, m_l = -3, m_s = +1/2
D.
n = 4, l = 3, m_l = +4, m_s = -1/2
Correct Answer:
n = 4, l = 3, m_l = +3, m_s = -1/2
Explanation:
An f-subshell is characterized by l = 3. For l = 3, m_l can range from -3 to +3, and m_s can be +1/2 or -1/2. The principal quantum number must be at least 4, so the given set is valid.
2. How many distinct 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. Each orbital can hold two electrons with opposite spins, giving a maximum capacity of 14 electrons.
3. Which set lists all possible magnetic quantum numbers for a 5f electron?
A.
-2, -1, 0, +1, +2
B.
-3, -2, -1, 0, +1, +2, +3
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:
The designation 5f gives l = 3 because f corresponds to l = 3. Therefore, m_l has seven possible values from -l to +l: -3, -2, -1, 0, +1, +2, and +3.
4. An f-subshell is completely filled. How many electrons in it must have m_s = +1/2?
A.
3
B.
7
C.
10
D.
14
Correct Answer:
7
Explanation:
An f-subshell contains seven orbitals. In a completely filled subshell, each orbital contains one electron with m_s = +1/2 and one with m_s = -1/2. Thus, seven electrons have m_s = +1/2.
5. What is the number of angular nodes associated with an electron in any f-subshell?
A.
1
B.
2
C.
3
D.
4
Correct Answer:
3
Explanation:
The number of angular nodes in an orbital equals the azimuthal quantum number l. Since an f-subshell has l = 3, each f orbital has three angular nodes.
6. Which statement correctly distinguishes the 4f and 5f subshells while retaining their common f-subshell characteristics?
A.
Both have l = 3 and seven orbitals, but 5f has a higher principal quantum number
B.
4f has l = 3, whereas 5f has l = 4
C.
Both have the same principal quantum number but different numbers of orbitals
D.
4f has seven orbitals, whereas 5f has five orbitals
Correct Answer:
Both have l = 3 and seven orbitals, but 5f has a higher principal quantum number
Explanation:
The letter f specifies l = 3 for both subshells, so each contains seven orbitals and can hold fourteen electrons. Their principal quantum numbers differ: n = 4 for 4f and n = 5 for 5f.
7. Which electron description is impossible for an f-subshell because of the allowed range of m_l?
A.
4f, m_l = -3
B.
5f, m_l = 0
C.
6f, m_l = +2
D.
4f, m_l = -4
Correct Answer:
4f, m_l = -4
Explanation:
For every f-subshell, l = 3 and m_l can only range from -3 to +3. Therefore, m_l = -4 is not allowed for a 4f electron.
8. If an f-subshell contains 11 electrons, what is the number of unpaired electrons in that subshell according to Hund's rule?
A.
1
B.
2
C.
3
D.
5
Correct Answer:
3
Explanation:
An f-subshell has seven orbitals. The first seven electrons occupy separate orbitals, and the next four pair in four of them. Thus, three orbitals remain singly occupied, giving three unpaired electrons.
9. Which combination correctly gives the azimuthal quantum number, number of orbitals, and maximum electron capacity of an f-subshell?
A.
l = 2, 5 orbitals, 10 electrons
B.
l = 3, 7 orbitals, 14 electrons
C.
l = 4, 9 orbitals, 18 electrons
D.
l = 1, 3 orbitals, 6 electrons
Correct Answer:
l = 3, 7 orbitals, 14 electrons
Explanation:
The f designation corresponds to l = 3. The number of orbitals is 2l + 1 = 7, and with two electrons per orbital, the maximum capacity is 14 electrons.
10. For a 4f subshell, which statement about the possible electron states is correct?
A.
It has seven allowed m_l values and two allowed spin values for each m_l
B.
It has four allowed m_l values and three allowed spin values for each m_l
C.
It has three allowed m_l values and seven allowed spin values for each m_l
D.
It has one allowed m_l value and fourteen allowed spin values for that value
Correct Answer:
It has seven allowed m_l values and two allowed spin values for each m_l
Explanation:
For 4f, l = 3, giving seven m_l values from -3 through +3. Each orbital specified by m_l permits two spin projections, m_s = +1/2 and -1/2, resulting in fourteen possible electron states.
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