MCQ 11
Which of the following is NOT a consequence of the quantum mechanical model?
A) Electrons exhibit wave-particle duality.
B) The quantization of energy levels in atoms.
C) Electrons have definite paths around the nucleus.
D) The existence of orbitals.
Answer: C) Electrons have definite paths around the nucleus.
Explanation: In the quantum mechanical model, electrons do not have definite paths but exist in probabilistic orbitals. The model allows for wave-particle duality and quantized energy levels.
MCQ 12
What is the maximum number of electrons in a shell with principal quantum number n = 3?
A) 2
B) 8
C) 18
D) 32
Answer: C) 18.
MCQ 13
Which principle states that no two electrons in an atom can have the same set of quantum numbers?
A) Hund’s Rule
B) Aufbau Principle
C) Pauli Exclusion Principle
D) Heisenberg Uncertainty Principle
Answer: C) Pauli Exclusion Principle.
Explanation: The Pauli Exclusion Principle asserts that no two electrons in the same atom can have identical quantum numbers, ensuring that each electron occupies a unique state.
MCQ 14
Which of the following statements about the p orbitals is true?
A) They can hold a maximum of 2 electrons.
B) They are spherical in shape.
C) There are three p orbitals in each energy level starting from n = 2.
D) They exist only in the n = 1 shell.
Answer: C) There are three p orbitals in each energy level starting from n = 2.
Explanation: Each p subshell contains three orbitals, which can hold a total of 6 electrons. P orbitals are not spherical; they have a dumbbell shape and start appearing from the second energy level.
MCQ 15
Which of the following is a valid set of quantum numbers for an electron in a 3p orbital?
A) n = 3, l = 2, m_l = 0, m_s = +1/2
B) n = 3, l = 1, m_l = -1, m_s = -1/2
C) n = 2, l = 1, m_l = 1, m_s = +1/2
D) n = 1, l = 0, m_l = 1, m_s = -1/2
Answer: B) n = 3, l = 1, m_l = -1, m_s = -1/2.
Explanation: For a 3p orbital, the principal quantum number (n) is 3, the azimuthal quantum number (l) is 1 (for p orbitals), and the magnetic quantum number (m_l) can be -1, 0, or +1. The spin quantum number (m_s) can be +1/2 or -1/2.
MCQ 16
Which of the following describes the wave-particle duality of electrons?
A) Electrons can be in only one state at a time.
B) Electrons behave as both particles and waves.
C) Electrons do not exhibit any wave-like properties.
D) Electrons have a definite mass and charge.
Answer: B) Electrons behave as both particles and waves.
Explanation: Wave-particle duality is a fundamental concept in quantum mechanics, indicating that electrons exhibit properties of both particles and waves depending on the experiment.
MCQ 17
What does the term “degenerate orbitals” refer to?
A) Orbitals that are filled in the same energy level.
B) Orbitals that have the same energy level.
C) Orbitals that contain the same number of electrons.
D) Orbitals that have different shapes.
Answer: B) Orbitals that have the same energy level.
Explanation: Degenerate orbitals refer to orbitals that have the same energy, such as the three p orbitals in a given shell, which are equal in energy.
MCQ 18
In the hydrogen atom, what is the energy of an electron in the n = 1 level?
A) -13.6 eV
B) 0 eV
C) +13.6 eV
D) -1.51 eV
Answer: A) -13.6 eV.
Explanation: In the hydrogen atom, the energy of the electron in the n = 1 level is -13.6 eV. This negative value indicates that the electron is bound to the nucleus.
MCQ 19
According to Hund’s Rule, how should electrons be distributed in degenerate orbitals?
A) Pair up in the same orbital before filling others.
B) Fill each orbital singly before pairing.
C) Randomly fill orbitals.
D) Fill the lowest energy orbitals first.
Answer: B) Fill each orbital singly before pairing.
Explanation: Hund’s Rule states that electrons will occupy degenerate orbitals singly with parallel spins before any orbital is doubly occupied, maximizing total spin.
MCQ 20
Which of the following correctly describes the d orbitals?
A) They have a dumbbell shape.
B) There are five d orbitals in a d subshell.
C) They can hold a maximum of 6 electrons.
D) They appear in energy levels starting from n = 1.
Answer: B) There are five d orbitals in a d subshell.
Explanation: The d subshell contains five orbitals, and it can hold a maximum of 10 electrons. D orbitals have more complex shapes compared to s and p orbitals and start from the n = 3 level.
Leave a comment