chemistry : class11 Azimuthal quantum number : Concept of subshells : Structure of Atom MCQ Questions and Answers
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Azimuthal quantum number
MCQ questions and answers.
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MCQ Questions
1. For an electron in the fourth principal shell, which set gives all possible subshells as determined by the azimuthal quantum number?
A.
l = 0, 1, 2, 3
B.
l = 1, 2, 3, 4
C.
l = 0, 1, 2, 3, 4
D.
l = 0, 2, 4
Correct Answer:
l = 0, 1, 2, 3
Explanation:
For a shell with principal quantum number n, the azimuthal quantum number l can have integral values from 0 to n - 1. Thus, for n = 4, l = 0, 1, 2, and 3, corresponding to 4s, 4p, 4d, and 4f subshells.
2. Which azimuthal quantum number identifies a subshell whose orbital angular momentum magnitude is sqrt(6) h-bar?
A.
l = 1
B.
l = 2
C.
l = 3
D.
l = 6
Correct Answer:
l = 2
Explanation:
The orbital angular momentum magnitude is given by sqrt[l(l + 1)] h-bar. For l = 2, this becomes sqrt(2 x 3) h-bar = sqrt(6) h-bar.
3. An electron is described as occupying a 5d subshell. What is the value of its azimuthal quantum number, and what does it indicate?
A.
l = 1; a p subshell
B.
l = 2; a d subshell
C.
l = 3; an f subshell
D.
l = 5; a g subshell
Correct Answer:
l = 2; a d subshell
Explanation:
The spectroscopic subshell notation is related to l by s = 0, p = 1, d = 2, and f = 3. Therefore, a 5d subshell has l = 2.
4. Which proposed subshell is impossible because its azimuthal quantum number is not allowed for the stated principal shell?
A.
3p
B.
4f
C.
5d
D.
2d
Correct Answer:
2d
Explanation:
For n = 2, the allowed values of l are only 0 and 1, corresponding to 2s and 2p. A d subshell requires l = 2, so 2d is not permitted.
5. A subshell has an azimuthal quantum number l = 3. Which statement correctly characterizes it?
A.
It is an s subshell with one orbital
B.
It is a p subshell with three orbitals
C.
It is a d subshell with five orbitals
D.
It is an f subshell with seven orbitals
Correct Answer:
It is an f subshell with seven orbitals
Explanation:
The value l = 3 corresponds to an f subshell. The number of orbitals in a subshell is 2l + 1, giving 2(3) + 1 = 7 orbitals.
6. Which sequence correctly represents the subshell labels as the azimuthal quantum number increases from l = 0 to l = 4?
A.
s, p, d, f, g
B.
s, d, p, f, g
C.
p, s, d, f, g
D.
s, p, f, d, g
Correct Answer:
s, p, d, f, g
Explanation:
Subshell notation follows the sequence l = 0 for s, l = 1 for p, l = 2 for d, l = 3 for f, and l = 4 for g.
7. Which pair of subshells has the same azimuthal quantum number but belongs to different principal shells?
A.
3p and 4p
B.
3s and 3p
C.
4d and 5f
D.
2p and 3d
Correct Answer:
3p and 4p
Explanation:
Both p subshells have l = 1, regardless of their principal shell. Therefore, 3p and 4p have the same azimuthal quantum number but different principal quantum numbers.
8. A subshell is known to contain five orbitals. Which value of the azimuthal quantum number must it possess?
A.
l = 1
B.
l = 2
C.
l = 3
D.
l = 4
Correct Answer:
l = 2
Explanation:
The number of orbitals in a subshell is 2l + 1. Setting this equal to five gives 2l + 1 = 5, so l = 2, which identifies a d subshell.
9. For which principal shell is an f subshell first possible according to the allowed values of the azimuthal quantum number?
A.
n = 2
B.
n = 3
C.
n = 4
D.
n = 5
Correct Answer:
n = 4
Explanation:
An f subshell requires l = 3. Since l can range only from 0 to n - 1, the smallest possible shell has n = 4, allowing l = 3.
10. Two subshells have azimuthal quantum numbers l = 1 and l = 3, respectively. What is the difference between their numbers of orbitals?
A.
Two orbitals
B.
Four orbitals
C.
Six orbitals
D.
Eight orbitals
Correct Answer:
Four orbitals
Explanation:
The number of orbitals is 2l + 1. For l = 1 there are 3 orbitals, while for l = 3 there are 7 orbitals. Their difference is 7 - 3 = 4 orbitals.