chemistry : class11 d-Orbitals : Concept of orbitals : Structure of Atom MCQ Questions and Answers
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d-Orbitals
MCQ questions and answers.
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MCQ Questions
1. For a hydrogen-like atom, which set of quantum numbers correctly represents a 4d orbital?
A.
n = 4, l = 2, m_l = -2
B.
n = 4, l = 3, m_l = +2
C.
n = 3, l = 2, m_l = +3
D.
n = 4, l = 1, m_l = 0
Correct Answer:
n = 4, l = 2, m_l = -2
Explanation:
A d orbital is characterized by l = 2. For n = 4, the allowed magnetic quantum numbers are -2, -1, 0, +1, and +2, so m_l = -2 is valid.
2. How many angular nodes and radial nodes are present in a 4d orbital?
A.
2 angular nodes and 1 radial node
B.
1 angular node and 2 radial nodes
C.
2 angular nodes and 2 radial nodes
D.
4 angular nodes and 0 radial nodes
Correct Answer:
2 angular nodes and 1 radial node
Explanation:
For a d orbital, l = 2, so the number of angular nodes is 2. The number of radial nodes is n - l - 1 = 4 - 2 - 1 = 1.
3. Which statement correctly distinguishes the five d orbitals in an isolated atom?
A.
They have different principal quantum numbers but identical shapes.
B.
They have the same n and l values but differ in their m_l values and spatial orientations.
C.
They have different l values but the same m_l value.
D.
They differ only in the number of radial nodes.
Correct Answer:
They have the same n and l values but differ in their m_l values and spatial orientations.
Explanation:
The five d orbitals belong to the same subshell, so they have identical n and l values. Their five possible m_l values correspond to different orientations in space.
4. Which d orbital has its lobes directed between the x- and y-axes in the xy-plane?
A.
d_x2-y2
B.
d_xy
C.
d_xz
D.
d_z2
Correct Answer:
d_xy
Explanation:
The d_xy orbital lies in the xy-plane, with its four lobes directed between the x- and y-axes. In contrast, d_x2-y2 has lobes directed along those axes.
5. Which nodal-plane description is correct for the d_xz orbital?
A.
It has the xy-plane as a nodal plane.
B.
It has the yz-plane as a nodal plane.
C.
It has the xz-plane as a nodal plane.
D.
It has no angular nodal plane.
Correct Answer:
It has the yz-plane as a nodal plane.
Explanation:
The angular part of d_xz is proportional to xz. It becomes zero when x = 0, which defines the yz-plane, and when z = 0, which defines the xy-plane. Thus, d_xz has both the yz-plane and xy-plane as nodal planes; among the choices, the yz-plane is correct.
6. Which statement about the d_z2 orbital is correct?
A.
It consists of four lobes lying entirely in the xy-plane.
B.
It has two elongated lobes along the z-axis and a torus-shaped region around the nucleus in the xy-plane.
C.
It has four lobes directed between the x- and y-axes.
D.
It has one spherical nodal surface and no angular nodes.
Correct Answer:
It has two elongated lobes along the z-axis and a torus-shaped region around the nucleus in the xy-plane.
Explanation:
The d_z2 orbital has two major lobes oriented along the z-axis and a toroidal region around the nucleus in the xy-plane. Despite its appearance, it still has two angular nodes.
7. For the five d orbitals of a given shell, what is the total number of possible values of m_l?
A.
2
B.
3
C.
5
D.
7
Correct Answer:
5
Explanation:
For d orbitals, l = 2. Therefore, m_l can take the values -2, -1, 0, +1, and +2, giving five possible orientations.
8. Which pair of d orbitals has lobes directed along the Cartesian axes rather than between them?
A.
d_xy and d_xz
B.
d_xz and d_yz
C.
d_x2-y2 and d_z2
D.
d_xy and d_yz
Correct Answer:
d_x2-y2 and d_z2
Explanation:
The d_x2-y2 orbital has lobes along the x- and y-axes, while d_z2 has lobes along the z-axis. The other three orbitals have lobes oriented between coordinate axes.
9. A d orbital in the n = 5 shell has how many radial nodes?
A.
1
B.
2
C.
3
D.
4
Correct Answer:
2
Explanation:
For a d orbital, l = 2. The number of radial nodes is n - l - 1 = 5 - 2 - 1 = 2.
10. Which statement correctly compares the angular probability distributions of d_xy and d_x2-y2 orbitals?
A.
Both have spherical symmetry, but d_xy has more radial nodes.
B.
Both have four lobes in the xy-plane, but their lobes are rotated by 45 degrees relative to each other.
C.
d_xy has lobes along the axes, whereas d_x2-y2 has lobes between the axes.
D.
d_x2-y2 has two lobes along the z-axis, whereas d_xy has four lobes in the xy-plane.
Correct Answer:
Both have four lobes in the xy-plane, but their lobes are rotated by 45 degrees relative to each other.
Explanation:
Both d_xy and d_x2-y2 contain four lobes in the xy-plane. The lobes of d_x2-y2 point along the x- and y-axes, whereas those of d_xy point between these axes, producing a 45-degree rotation.
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