Quantum Mechanical Model of the Atom — NEET Chemistry MCQs with Solutions
Free NEET Chemistry Quantum Mechanical Model of the Atom MCQs with step-by-step solutions (42 questions). Part of Atomic Structure. Practise online on Prepizo — no login needed.
▶ Practise Quantum Mechanical Model of the Atom online (free)
Questions with solutions
Q1 — Quantum Mechanical Model of the Atom · easy · theory
The quantum mechanical model of the atom is based on the wave equation developed by:
A. Niels Bohr
B. Erwin Schrödinger ✓ Correct
C. John Dalton
D. J. J. Thomson
Solution: Schrödinger formulated the wave equation whose solutions (wave functions) describe the quantum mechanical model of the atom.
Q2 — Quantum Mechanical Model of the Atom · medium · theory
In the quantum mechanical model, the square of the wave function (ψ²) represents the:
A. Charge of the electron
B. Exact path of the electron
C. Total energy of the electron
D. Probability density of finding the electron ✓ Correct
Solution: ψ² gives the probability density — the likelihood of finding the electron in a small region of space around a point.
Q3 — Quantum Mechanical Model of the Atom · medium · theory
The wave function ψ itself:
A. Gives the exact position of the electron
B. Has no direct physical meaning; it is the amplitude of the electron wave ✓ Correct
C. Represents the charge density directly
D. Equals the energy of the electron
Solution: ψ is the amplitude of the electron wave and has no direct physical significance by itself; only ψ² (probability density) is physically meaningful.
Q4 — Quantum Mechanical Model of the Atom · easy · theory
The principal quantum number (n) mainly determines the:
A. Shape of the orbital
B. Size and energy of the orbital ✓ Correct
C. Orientation of the orbital
D. Spin of the electron
Solution: n (= 1, 2, 3, …) fixes the main energy level and the size of the orbital; larger n means larger, higher-energy orbitals.
Q5 — Quantum Mechanical Model of the Atom · easy · theory
The azimuthal (subsidiary) quantum number (l) determines the:
A. Spin direction of the electron
B. Orientation of the orbital in space
C. Size of the orbital
D. Shape of the orbital ✓ Correct
Solution: l defines the subshell and hence the shape of the orbital (s, p, d, f).
Q6 — Quantum Mechanical Model of the Atom · medium · theory
For a given value of the principal quantum number n, the azimuthal quantum number l can take values:
A. 0 to (n − 1) ✓ Correct
B. −l to +l
C. 0 to n
D. 1 to n
Solution: l ranges from 0 up to (n − 1), giving n possible subshells for the nth shell.
Q7 — Quantum Mechanical Model of the Atom · medium · numerical
The value of the azimuthal quantum number (l) for an f subshell is:
A. 0
B. 3 ✓ Correct
C. 1
D. 2
Solution: By convention l = 0 (s), 1 (p), 2 (d), 3 (f); so an f subshell has l = 3.
Q8 — Quantum Mechanical Model of the Atom · medium · theory
The magnetic quantum number (mₗ) can take values:
A. 1 to l
B. −l to +l (including 0) ✓ Correct
C. ±1/2
D. 0 to n − 1
Solution: mₗ describes the orientation of an orbital and takes the (2l + 1) values from −l to +l, including 0.
Q9 — Quantum Mechanical Model of the Atom · medium · theory
The number of orbitals in a subshell of azimuthal quantum number l is:
A. n²
B. l + 1
C. 2l + 1 ✓ Correct
D. 2l
Solution: The number of orientations (values of mₗ) is 2l + 1, which equals the number of orbitals in the subshell.
Q10 — Quantum Mechanical Model of the Atom · easy · numerical
The number of orbitals present in a d subshell is:
A. 5 ✓ Correct
B. 1
C. 3
D. 7
Solution: For a d subshell l = 2, so orbitals = 2l + 1 = 5.
Q11 — Quantum Mechanical Model of the Atom · medium · numerical
The total number of orbitals in the shell with n = 3 is:
A. 6
B. 3
C. 18
D. 9 ✓ Correct
Solution: Number of orbitals in a shell = n² = 3² = 9 (one 3s, three 3p, five 3d).
Q12 — Quantum Mechanical Model of the Atom · medium · numerical
The maximum number of electrons that can be accommodated in the shell with n = 3 is:
A. 18 ✓ Correct
B. 9
C. 32
D. 8
Solution: Maximum electrons in a shell = 2n² = 2 × 3² = 18.
Q13 — Quantum Mechanical Model of the Atom · medium · numerical
The maximum number of electrons that an f subshell can hold is:
A. 6
B. 14 ✓ Correct
C. 2
D. 10
Solution: An f subshell has 7 orbitals (2l + 1 with l = 3); each holds 2 electrons, so 14 in total.
Q14 — Quantum Mechanical Model of the Atom · easy · theory
The spin quantum number (mₛ) of an electron can have the values:
A. −l to +l
B. 0 or 1
C. 1, 2, 3, …
D. +1/2 or −1/2 ✓ Correct
Solution: The electron spin quantum number is either +1/2 or −1/2, representing the two spin orientations.
Q15 — Quantum Mechanical Model of the Atom · medium · theory
Which of the following sets of quantum numbers is NOT permitted?
A. n = 2, l = 1, mₗ = −1
B. n = 2, l = 2, mₗ = 0 ✓ Correct
C. n = 1, l = 0, mₗ = 0
D. n = 3, l = 2, mₗ = +2
Solution: For n = 2, l can only be 0 or 1 (l ≤ n − 1). So l = 2 is not allowed when n = 2.
Q16 — Quantum Mechanical Model of the Atom · easy · theory
For a 3p orbital, the values of n and l are:
A. n = 3, l = 0
B. n = 3, l = 1 ✓ Correct
C. n = 3, l = 2
D. n = 1, l = 3
Solution: The number 3 is the principal quantum number (n = 3) and "p" corresponds to l = 1.
Q17 — Quantum Mechanical Model of the Atom · medium · numerical
The number of subshells present in the shell with n = 4 is:
A. 4 ✓ Correct
B. 16
C. 2
D. 3
Solution: The number of subshells equals n. For n = 4 there are 4 subshells: 4s, 4p, 4d, 4f.
Q18 — Quantum Mechanical Model of the Atom · easy · theory
The shape of an s orbital is:
A. Spherical ✓ Correct
B. Pyramidal
C. Dumb-bell
D. Double dumb-bell
Solution: An s orbital is spherically symmetrical about the nucleus.
Q19 — Quantum Mechanical Model of the Atom · easy · theory
The shape of a p orbital is:
A. Cubic
B. Spherical
C. Dumb-bell shaped ✓ Correct
D. Cloverleaf (double dumb-bell)
Solution: Each p orbital has a dumb-bell shape with two lobes on either side of the nucleus.
Q20 — Quantum Mechanical Model of the Atom · medium · theory
The number of angular nodes (nodal planes) in an orbital is equal to:
A. n
B. n − 1
C. l ✓ Correct
D. n − l − 1
Solution: The number of angular nodes equals the azimuthal quantum number l.
Q21 — Quantum Mechanical Model of the Atom · medium · theory
The number of radial nodes in an orbital is given by:
A. n − 1
B. n + l
C. n − l − 1 ✓ Correct
D. l
Solution: Radial nodes = n − l − 1.
Q22 — Quantum Mechanical Model of the Atom · medium · theory
The total number of nodes in an orbital is equal to:
A. n
B. n − l
C. l
D. n − 1 ✓ Correct
Solution: Total nodes = radial nodes + angular nodes = (n − l − 1) + l = n − 1.
Q23 — Quantum Mechanical Model of the Atom · medium · numerical
The number of radial nodes in a 3s orbital is:
A. 2 ✓ Correct
B. 0
C. 1
D. 3
Solution: Radial nodes = n − l − 1 = 3 − 0 − 1 = 2.
Q24 — Quantum Mechanical Model of the Atom · medium · numerical
The number of angular nodes (nodal planes) in a 2p orbital is:
A. 3
B. 0
C. 1 ✓ Correct
D. 2
Solution: Angular nodes = l. For a p orbital l = 1, so there is 1 nodal plane.
Q25 — Quantum Mechanical Model of the Atom · medium · numerical
The number of angular nodes in a d orbital is:
A. 3
B. 1
C. 2 ✓ Correct
D. 0
Solution: For a d orbital l = 2, so it has 2 angular nodes.
Q26 — Quantum Mechanical Model of the Atom · medium · numerical
The total number of nodes present in a 3p orbital is:
A. 0
B. 3
C. 2 ✓ Correct
D. 1
Solution: Total nodes = n − 1 = 3 − 1 = 2 (one radial node and one angular node).
Q27 — Quantum Mechanical Model of the Atom · medium · theory
According to the (n + l) rule, an orbital with a lower value of (n + l) has:
A. The same energy as all others
B. Lower energy and is filled first ✓ Correct
C. Higher energy and is filled last
D. No definite energy
Solution: The orbital with the smaller (n + l) value is lower in energy and is filled first. If two orbitals have equal (n + l), the one with lower n fills first.
Q28 — Quantum Mechanical Model of the Atom · medium · theory
Which orbital is filled first, 4s or 3d, and why?
A. 3d, because it has the lower n value
B. 3d, because it has the lower (n + l) value
C. They fill at the same time
D. 4s, because it has the lower (n + l) value ✓ Correct
Solution: For 4s, n + l = 4 + 0 = 4; for 3d, n + l = 3 + 2 = 5. The lower value (4s) fills first.
Q29 — Quantum Mechanical Model of the Atom · medium · theory
The orbitals 3d and 4p have the same (n + l) value of 5. Which one is filled first?
A. 3d, because it has the lower value of n ✓ Correct
B. 4p, because it has the lower value of n
C. Both are filled simultaneously
D. 4p, because it has the higher value of l
Solution: When (n + l) is equal, the orbital with the lower n fills first — here 3d (n = 3) before 4p (n = 4).
Q30 — Quantum Mechanical Model of the Atom · easy · theory
Orbitals having the same energy are called:
A. Nodal orbitals
B. Degenerate orbitals ✓ Correct
C. Antibonding orbitals
D. Hybrid orbitals
Solution: Degenerate orbitals are orbitals of equal energy, e.g. the three p orbitals of a given subshell.