chemistry : class11 Angular nodes : Concept of orbitals : Structure of Atom MCQ Questions and Answers
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Angular nodes
MCQ questions and answers.
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MCQ Questions
1. An electron is described by a hydrogenic orbital with quantum numbers n = 5 and l = 3. How many angular nodes does its wavefunction possess?
A.
1
B.
2
C.
3
D.
5
Correct Answer:
3
Explanation:
The number of angular nodes in an orbital is equal to the azimuthal quantum number l. Therefore, an orbital with l = 3 has three angular nodes.
2. Which set of orbitals has exactly two angular nodes in each orbital?
A.
3s, 4s, and 5s
B.
2p, 3p, and 4p
C.
3d, 4d, and 5d
D.
4f, 5f, and 6f
Correct Answer:
3d, 4d, and 5d
Explanation:
All d orbitals have l = 2, so each d orbital contains exactly two angular nodes, regardless of its principal quantum number.
3. For a p orbital, the angular nodal surface is best described as:
A.
A spherical surface centered on the nucleus
B.
A plane passing through the nucleus
C.
Two concentric spherical surfaces
D.
A cylindrical surface parallel to the orbital axis
Correct Answer:
A plane passing through the nucleus
Explanation:
A p orbital has l = 1 and therefore one angular node. Its angular node is a plane that passes through the nucleus and separates the two opposite phases of the orbital.
4. Which orbital has an angular nodal plane coinciding with the yz-plane?
A.
p_x
B.
p_y
C.
p_z
D.
d_x2-y2
Correct Answer:
p_x
Explanation:
The p_x orbital is proportional to x, so its wavefunction becomes zero wherever x = 0. The surface x = 0 is the yz-plane, which is its angular nodal plane.
5. How many angular nodes are present in each of the five 3d orbitals?
A.
0
B.
1
C.
2
D.
3
Correct Answer:
2
Explanation:
For every d orbital, the azimuthal quantum number is l = 2. Hence, each of the five 3d orbitals has two angular nodes.
6. Which orbital has two mutually perpendicular angular nodal planes that contain the z-axis?
A.
d_xy
B.
d_x2-y2
C.
d_z2
D.
p_z
Correct Answer:
d_xy
Explanation:
The d_xy orbital has angular dependence proportional to xy. It is zero when x = 0 or y = 0, corresponding to the yz-plane and xz-plane. These two perpendicular planes both contain the z-axis.
7. Which statement correctly compares the angular nodes of 4p and 4d orbitals?
A.
4p has two angular nodes, while 4d has one
B.
Both 4p and 4d have the same number of angular nodes
C.
4p has one angular node, while 4d has two
D.
4p has no angular nodes, while 4d has two
Correct Answer:
4p has one angular node, while 4d has two
Explanation:
The 4p orbital has l = 1 and therefore one angular node, whereas the 4d orbital has l = 2 and therefore two angular nodes.
8. Which orbital is characterized by zero angular nodes despite having a nonzero principal quantum number?
A.
2s
B.
2p_x
C.
3d_xy
D.
4f_z3
Correct Answer:
2s
Explanation:
An s orbital has l = 0, so it has zero angular nodes. The principal quantum number determines the shell, but angular nodes depend specifically on l.
9. The angular part of the wavefunction for a particular orbital is proportional to xz. Which statement about its angular nodes is correct?
A.
It has one nodal plane, xz = 0
B.
It has two nodal planes, x = 0 and z = 0
C.
It has one spherical angular node
D.
It has no angular nodes because xz is nonnegative
Correct Answer:
It has two nodal planes, x = 0 and z = 0
Explanation:
The angular factor xz becomes zero when x = 0 or z = 0. Thus, the orbital has the two angular nodal planes x = 0, the yz-plane, and z = 0, the xy-plane.
10. An orbital has exactly three angular nodes. Which identification is necessarily correct?
A.
It is an s orbital
B.
It is a p orbital
C.
It is a d orbital
D.
It is an f orbital
Correct Answer:
It is an f orbital
Explanation:
The number of angular nodes equals l. Three angular nodes require l = 3, which corresponds to an f orbital.
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