Selected MCQ

Current Question
Which principle states that identical fermions cannot occupy the same quantum state?
  • A. Heisenberg principle
  • B. Pauli exclusion principle
  • C. Hund’s rule
  • D. Aufbau principle
Correct Answer: B
Explanation:
Fermions obey antisymmetric wavefunctions prohibiting identical states.
Related Question 1
In a Hilbert space formulation of quantum mechanics, physical states are represented by:
  • A. Real numbers
  • B. Vectors up to a global phase
  • C. Scalars only
  • D. Matrices only
Correct Answer: B
Explanation:
States are rays in Hilbert space, invariant under global phase.
Related Question 2
Which principle states particles are indistinguishable?
  • A. Pauli principle
  • B. Superposition principle
  • C. Indistinguishability principle
  • D. Correspondence principle
Correct Answer: C
Explanation:
Quantum particles of same type are identical.
Related Question 3
Which quantum number determines orbital shape?
  • A. Principal
  • B. Azimuthal
  • C. Magnetic
  • D. Spin
Correct Answer: B
Explanation:
Azimuthal quantum number defines orbital geometry.
Related Question 4
In quantum mechanics, the commutator ([x,p]) equals:
  • A. 0
  • B. (i\hbar)
  • C. (-i\hbar)
  • D. (\hbar^2)
Correct Answer: B
Explanation:
Position and momentum operators satisfy ([x,p]=i\hbar).
Related Question 5
In quantum mechanics, expectation value of an observable corresponds to:
  • A. Most probable value
  • B. Average measurement over many identical systems
  • C. Minimum energy
  • D. Maximum probability
Correct Answer: B
Explanation:
Expectation value is statistical mean of repeated measurements.