chemistry : class11 Magnetic Quantum Number : Concept of subshells : Structure of Atom MCQ Questions and Answers
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Magnetic Quantum Number
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MCQ Questions
1. For a subshell with azimuthal quantum number l = 4, how many distinct orientations are permitted by the magnetic quantum number?
A.
7
B.
8
C.
9
D.
10
Correct Answer:
9
Explanation:
The magnetic quantum number m_l ranges from -l to +l in integral steps. For l = 4, the values are -4, -3, -2, -1, 0, +1, +2, +3, and +4, giving 2l + 1 = 9 orientations.
2. Which set gives all possible magnetic quantum number values for a subshell having l = 3?
A.
{-3, -2, -1, 0, +1, +2, +3}
B.
{-2, -1, 0, +1, +2}
C.
{-3, -1, 0, +1, +3}
D.
{0, +1, +2, +3}
Correct Answer:
{-3, -2, -1, 0, +1, +2, +3}
Explanation:
For any given l, m_l can take every integral value from -l through +l. Thus, when l = 3, there are seven values from -3 to +3.
3. A subshell contains exactly seven orbitals. Which statement about its possible magnetic quantum numbers is correct?
A.
m_l ranges from -2 to +2
B.
m_l ranges from -3 to +3
C.
m_l ranges from -7 to +7
D.
m_l can have only positive integral values from 1 to 7
Correct Answer:
m_l ranges from -3 to +3
Explanation:
The number of orbitals in a subshell is 2l + 1. Seven orbitals imply l = 3, so m_l takes the seven integral values from -3 to +3.
4. Which of the following values of m_l is forbidden for an electron in a subshell with l = 2?
A.
-2
B.
-1
C.
+2
D.
+3
Correct Answer:
+3
Explanation:
For l = 2, the allowed magnetic quantum numbers are -2, -1, 0, +1, and +2. Therefore, +3 is not permitted.
5. The magnetic quantum number m_l = -2 can occur in how many different subshells characterized by l = 0, 1, 2, 3, and 4?
A.
1
B.
2
C.
3
D.
4
Correct Answer:
3
Explanation:
A value m_l = -2 is allowed only when l is at least 2. Among l = 0, 1, 2, 3, and 4, it occurs for l = 2, 3, and 4, giving three subshells.
6. Considering all subshells with l values 1, 2, and 3, how many orbitals possess m_l = 0?
A.
1
B.
2
C.
3
D.
6
Correct Answer:
3
Explanation:
Every subshell, regardless of its l value, includes exactly one orbital with m_l = 0. Therefore, the subshells with l = 1, 2, and 3 together contain three such orbitals.
7. In the n = 4 shell, how many orbitals can have the magnetic quantum number m_l = +2?
A.
1
B.
2
C.
3
D.
4
Correct Answer:
2
Explanation:
Within the n = 4 shell, the allowed l values are 0, 1, 2, and 3. The value m_l = +2 is possible only for l = 2 and l = 3. Each of these subshells has one orbital with m_l = +2, so there are two such orbitals.
8. How many distinct magnetic quantum number values are common to subshells with l = 2 and l = 4?
A.
3
B.
4
C.
5
D.
7
Correct Answer:
5
Explanation:
For l = 2, m_l ranges from -2 to +2. For l = 4, it ranges from -4 to +4. The common values are -2, -1, 0, +1, and +2, totaling five.
9. A subshell has eleven possible orientations. Which pair correctly identifies its l value and its extreme m_l values?
A.
l = 4; m_l = -4 and +4
B.
l = 5; m_l = -5 and +5
C.
l = 6; m_l = -6 and +6
D.
l = 11; m_l = -11 and +11
Correct Answer:
l = 5; m_l = -5 and +5
Explanation:
The number of orientations is 2l + 1. Setting 2l + 1 = 11 gives l = 5, and the extreme magnetic quantum number values are -5 and +5.
10. For l = 4, how many allowed magnetic quantum number values have a negative sign and an equal number have a positive sign?
A.
3 of each
B.
4 of each
C.
5 of each
D.
8 of each
Correct Answer:
4 of each
Explanation:
For l = 4, the values are -4, -3, -2, -1, 0, +1, +2, +3, and +4. There are four negative values and four positive values, with zero being neither positive nor negative.
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