MCQ 101
What does the principal quantum number (n) indicate?
A) Shape of the orbital
B) Size and energy level of the orbital
C) Orientation of the orbital
D) Spin of the electron
Answer: B) Size and energy level of the orbital.
Explanation: The principal quantum number (n) indicates the main energy level or shell in which an electron resides, reflecting the size and energy of the orbital.
MCQ 102
Which of the following quantum numbers describes the shape of an orbital?
A) Principal quantum number (n)
B) Azimuthal quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (s)
Answer: B) Azimuthal quantum number (l).
Explanation: The azimuthal quantum number (l) determines the shape of the orbital, with values corresponding to different types of orbitals (s, p, d, f).
MCQ 103
Which of the following orbitals can hold a maximum of 10 electrons?
A) s orbital
B) p orbital
C) d orbital
D) f orbital
Answer: C) d orbital.
Explanation: The d orbital can hold a maximum of 10 electrons since it consists of 5 sub-orbitals, each capable of holding 2 electrons.
MCQ 104
Which quantum number describes the orientation of an orbital?
A) Principal quantum number (n)
B) Azimuthal quantum number (l)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (s)
Answer: C) Magnetic quantum number (mₗ).
Explanation: The magnetic quantum number (mₗ) specifies the orientation of the orbital in space.
MCQ 105
What is the maximum number of electrons that can occupy the second energy level (n=2)?
A) 2
B) 8
C) 18
D) 32
Answer: B) 8.
MCQ 106
In which of the following does the electron occupy the highest energy state?
A) 1s
B) 2p
C) 3s
D) 3d
Answer: D) 3d.
Explanation: Among the given options, the 3d orbital has the highest energy state due to its location in the third shell.
MCQ 107
Which of the following describes the Pauli Exclusion Principle?
A) No two electrons can have the same set of four quantum numbers.
B) Electrons fill orbitals starting from the lowest energy level first.
C) Electrons in the same orbital must have opposite spins.
D) Both A and C.
Answer: D) Both A and C.
Explanation: The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers, and if two electrons are in the same orbital, they must have opposite spins.
MCQ 108
What does Hund’s Rule state?
A) Electrons occupy orbitals of the same energy singly before pairing up.
B) Electrons will fill lower energy orbitals before higher energy orbitals.
C) No two electrons can have the same set of quantum numbers.
D) The energy of an electron is quantized.
Answer: A) Electrons occupy orbitals of the same energy singly before pairing up.
Explanation: Hund’s Rule emphasizes that electrons will first fill degenerate orbitals (orbitals of the same energy) singly and only pair up when necessary.
MCQ 109
What is the electron configuration of a neutral nitrogen atom (atomic number 7)?
A) 1s² 2s² 2p¹
B) 1s² 2s² 2p³
C) 1s² 2s¹ 2p⁶
D) 1s² 2p⁵
Answer: B) 1s² 2s² 2p³.
Explanation: Nitrogen has 7 electrons, which are arranged in the electron configuration 1s² 2s² 2p³.
MCQ 110
Which of the following statements about the quantum mechanical model of the atom is true?
A) Electrons follow fixed orbits like planets around the sun.
B) The position of an electron can be precisely determined.
C) Electrons are found in probabilistic regions called orbitals.
D) The atom is primarily composed of solid matter.
Answer: C) Electrons are found in probabilistic regions called orbitals.
Explanation: The quantum mechanical model describes electrons as existing in probabilistic orbitals rather than fixed paths.
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