The branch of science dealing with the behaviour of light and matter on the atomic and subatomic scale is known as quantum mechanics. A group of physicists, including Max Born, Wolfgang Pauli and Werner Heisenberg, coined the word “Quantum Mechanics” in the early 1920s at the University of Göttingen. Both matter and radiation acquire the characteristics of waves and particles at the fundamental level.
Important Questions on Quantum Mechanics
1) Quantum Numbers are solutions of _____.
a) Schrodinger’s Wave Equation
b) Hamiltonian Operator
c) Heisenberg’s Uncertainty Principle
d) Einstein’s Mass-Energy Relation
Correct Option: (a)
Explanation: Using the Schrodinger Wave Equation, when the wave function for an atom is solved, then the obtained solutions are called the Quantum Number, which is fundamentally n, l and m.
2) The shell to which the electron belongs is given by which quantum number?
a) m
b) s
c) n
d) l
Correct Option: (c)
Explanation: The energy of the shell is dependent on ‘n’, and the principal quantum number n gives the shell to which the electron belongs.
3) The maximum number of electrons in a shell is?
a) 2n
b) 2n2
c) 3n2
d) n2
Correct Option: (b)
Explanation: The number of orbitals present in a shell is given by n2, while the total number of electrons in a shell is given by: 2n2, which is twice the total number of orbitals present in that shell.
4) The shape of the atomic orbital of the subshell is given by which of the following quantum numbers?
a) m
b) s
c) n
d) l
Correct Option: (d)
Explanation: The shape of the atomic orbital subshell can be determined with the help of the Azimuthal quantum number l. It helps us in finding the subshell to which the electron belongs.
5) Which among the following is the range of Azimuthal Quantum Number, l?
a) 0 to n-1
b) 0 to s
c) 0 to n
d) 0 to s-1
Correct Option: (a)
Explanation: The Azimuthal Quantum number value, l, fluctuates from 0 to n-1. It helps us in finding the subshell to which the electron belongs.
6) What are the total values of the magnetic quantum number?
a) 3n
b) 3l
c) 3n + 1
d) 2l + 1
Correct Option: (d)
Explanation: The total values of me are 2l + 1. The magnetic quantum number denotes the orientation of electrons in an atom, and they vary from –l to +l.
7) Principles of Quantum Mechanics can be used to derive the Schrodinger Wave equation.
a) True
b) False
Correct Option: (b)
Explanation: Schrodinger equation cannot be derived from other physics principles because it is an elementary principle in itself. It can be only verified with other principles.
8) What does the principal quantum number describe?
a) The spin of the electron
b) Spatial orientation of the orbital
c) The shape of the orbital
d) Energy and size of the orbit
Correct Option: (d)
Explanation: The principal quantum number among the four quantum numbers describes the size and energy of the orbit. For shells K, L, M, N and O, n is given by 1, 2, 3, 4 and 5.
The symbol “n represents it”.
9) Among the following set of quantum numbers, which one is not valid?
a) n = 5, l = 2, m = 0, s = 1/2
b) n = 5, l = 3, m = 2, s = 1/2
c) n = 1, l = 2, m = 0, s = 1/2
d) n = 5, l = 2, m = 0, s = -1/2
Correct Option: (c)
Explanation: Sine, the value of an azimuthal quantum number should lie only between 0 and n-1, where n is the principal quantum number. Therefore, the set of quantum numbers n = 1, l = 2, m = 0, s = 1/2, is not valid.
10) The motion of a wave packet is analogous to _____.
a) Photons
b) Electrons
c) Classical Particle
d) Quantum Particle
Correct Option: (c)
Explanation: The motion of a material/classical particle is similar to a collection of waves or a wave packet. Such an expression can be derived using the basic principles of motion.
Practice Questions
1) What is quantum mechanics?
2) What is Schrodinger’s wave equation?
3) What is electromagnetic radiation?
4) Define photons.
5) Explain Einstein’s mass-energy relation.
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