MCQ 111
What is the shape of the s orbital?
A) Dumbbell-shaped
B) Spherical
C) Double dumbbell
D) Linear
Answer: B) Spherical.
Explanation: The s orbital has a spherical shape, with the probability density of finding an electron uniformly distributed around the nucleus.
MCQ 112
What is the primary characteristic of a p orbital?
A) It is spherical in shape.
B) It can hold a maximum of 2 electrons.
C) It has a dumbbell shape.
D) It has no angular momentum.
Answer: C) It has a dumbbell shape.
Explanation: The p orbital is characterized by its dumbbell shape and can hold a maximum of 6 electrons across its three orientations.
MCQ 113
Which of the following statements about the d orbital is correct?
A) There are three d orbitals in a given energy level.
B) The d orbital is always higher in energy than the p orbital in the same principal energy level.
C) There are five d orbitals in a given energy level.
D) The d orbital can hold a maximum of 4 electrons.
Answer: C) There are five d orbitals in a given energy level.
Explanation: The d subshell consists of five orbitals, allowing it to hold a maximum of 10 electrons.
MCQ 114
What phenomenon describes the energy levels of electrons in an atom?
A) Electromagnetic radiation
B) Quantum mechanics
C) Classical mechanics
D) Thermodynamics
Answer: B) Quantum mechanics.
Explanation: Quantum mechanics explains the behavior of electrons and the quantized energy levels in atoms.
MCQ 115
Which of the following is true about electromagnetic radiation?
A) It travels at the speed of sound.
B) It consists of particles known as electrons.
C) It exhibits both wave-like and particle-like properties.
D) It cannot be quantified.
Answer: C) It exhibits both wave-like and particle-like properties.
Explanation: Electromagnetic radiation displays dual characteristics, behaving as both waves and particles (photons).
MCQ 116
Which quantum number cannot be negative?
A) Azimuthal quantum number (l)
B) Principal quantum number (n)
C) Magnetic quantum number (mₗ)
D) Spin quantum number (s)
Answer: B) Principal quantum number (n).
Explanation: The principal quantum number (n) is always a positive integer (1, 2, 3, …).
MCQ 117
What does the term “photoelectric effect” refer to?
A) The emission of electrons when light hits a material.
B) The absorption of light by an electron.
C) The generation of heat from light.
D) The reflection of light off a surface.
Answer: A) The emission of electrons when light hits a material.
Explanation: The photoelectric effect is the phenomenon where electrons are emitted from a material when it is exposed to light of sufficient energy.
MCQ 118
What is the uncertainty principle formulated by Heisenberg?
A) It states that the position and momentum of an electron can be precisely known.
B) It states that the energy of a system is always conserved.
C) It states that the position and momentum of an electron cannot be simultaneously measured with absolute precision.
D) It states that electrons exist in fixed orbits.
Answer: C) It states that the position and momentum of an electron cannot be simultaneously measured with absolute precision.
Explanation: Heisenberg’s uncertainty principle highlights the fundamental limit in measuring both the position and momentum of a particle at the same time.
MCQ 119
Which principle explains why electrons fill orbitals from lowest to highest energy?
A) Hund’s Rule
B) Pauli Exclusion Principle
C) Aufbau Principle
D) Dalton’s Law
Answer: C) Aufbau Principle
MCQ 120
In which of the following transitions does an electron absorb energy?
A) n=3 to n=2
B) n=2 to n=3
C) n=1 to n=2
D) Both B and C
Answer: D) Both B and C.
Explanation: Electrons absorb energy when moving from a lower energy level (n=2 or n=1) to a higher one (n=3).
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