Free Quantum Numbers MCQs with Answers

• A. shape of orbital
• B. main energy level and distance from the nucleus
• C. orientation of the orbital in space
• D. direction of spin

Explanation: The principal quantum number sets the shell, and therefore the main energy level and the average distance of the electron from the…

• A. Three
• B. Five
• C. Seven
• D. Nine

Explanation: For the d subshell l equals 2, so m runs from minus 2 to plus 2, giving five values and therefore five orbitals.

• A. n = 2, l = 1, m = 0
• B. n = 3, l = 2, m = -2
• C. n = 2, l = 2, m = 1
• D. n = 4, l = 0, m = 0

Explanation: The azimuthal quantum number l is restricted to values from 0 up to n minus 1, so with n equal to 2 the only allowed values of l are 0 and…

• A. 8
• B. 10
• C. 18
• D. 32

Explanation: The capacity of a shell is 2n squared, so for n equal to 3 that is 2 times 9, which is 18.

• A. the shape of the orbital
• B. the main energy level and the average distance of the electron from the nucleus
• C. the orientation of the orbital in space
• D. the direction of electron spin

Explanation: The value of n fixes the shell, so a larger n means a higher energy and an electron held further out on average.

• A. 0 only
• B. 0 and 1
• C. 0, 1 and 2
• D. 1, 2 and 3

Explanation: The azimuthal quantum number runs from 0 up to n minus 1, so for the third shell it takes the values 0, 1 and 2, corresponding to the 3s…

• A. 8
• B. 18
• C. 32
• D. 2

Explanation: Shell capacity is 2n squared, so for n equal to 3 the maximum is 2 multiplied by 9, that is 18, made up of 2 in 3s, 6 in 3p and 10 in 3d.

• A. 0 only
• B. minus 1, 0 and plus 1
• C. minus 2 to plus 2
• D. plus 1 only

Explanation: The magnetic quantum number runs from minus l to plus l, and for a p subshell l equals 1, giving three values that correspond to the three…

• A. n equals 2, l equals 1, m equals 0
• B. n equals 3, l equals 2, m equals minus 2
• C. n equals 2, l equals 2, m equals 1
• D. n equals 1, l equals 0, m equals 0

Explanation: The azimuthal quantum number can never equal or exceed n, so l equal to 2 is impossible when n is 2, which would describe a non existent…

• A. n=2, l=1, m=0, s=+1/2
• B. n=3, l=0, m=0, s=-1/2
• C. n=2, l=2, m=1, s=+1/2
• D. n=1, l=0, m=0, s=+1/2

Explanation: The azimuthal quantum number can only run from 0 up to n minus 1, so with n equal to 2 the value of l cannot reach 2, and the set…

• A. Pauli exclusion principle
• B. Hund's rule
• C. Aufbau's principle
• D. Le-Chatelier's principle

Explanation: Aufbau is a German word meaning 'building up' and is not the name of a scientist; the Aufbau principle describes filling lower-energy…

• A. Arithmetical values
• B. Numerical values
• C. Leometric values
• D. Logical values

Explanation: Quantum numbers are numerical values that specify an electron's energy level, subshell, orbital orientation and spin.

• A. n=2,l=1,m1=0,ms=+1/2
• B. n=2,l=1,m1=-1,ms=+1/2
• C. n=2,l=0,m1=0,ms=-1/2
• D. n=2,l=2,m1=1,ms=-1/2

Explanation: For n = 2, the azimuthal quantum number l can only be 0 or 1, so l = 2 is not allowed; option d is therefore invalid.

• A. e/m ratio of an electron
• B. Spin of an electron
• C. Angular momentum of an electron
• D. Magnetic momentum of an electron

Explanation: The azimuthal quantum number, l, identifies the subshell and therefore determines the electron's orbital angular momentum, whose magnitude…

• A. Size of orbitals
• B. Shape of orbitals
• C. Orientation of orbitals
• D. All of the above

Explanation: The magnetic quantum number, ml, gives the orientation of an orbital in space within a subshell.

• A. n
• B. 1
• C. m
• D. s

Explanation: The principal quantum number, n, specifies the main energy level and is therefore the quantum number most directly associated with an…

• A. 1
• B. 3
• C. 5
• D. 7

Explanation: For azimuthal quantum number l = 3, the magnetic quantum number m can have seven values: -3, -2, -1, 0, +1, +2 and +3.

• A. Principal
• B. Azimuthal
• C. Magnetic
• D. Spin

Explanation: The letters s, p, d and f represent subshells identified by the azimuthal quantum number, l.

• A. de-Broglie
• B. Plancks
• C. Schrodinger
• D. Heisenberg

Explanation: Solving Schrödinger's wave equation for an electron gives the principal, azimuthal and magnetic quantum numbers, which describe its energy…

• A. Degenerate orbitals
• B. Bonding molecular orbitals
• C. Anti bonding molecular orbitals
• D. Half filled orbitals

Explanation: Orbitals having the same energy are called degenerate orbitals, such as the three p orbitals in an isolated atom.