Question

In a given atom no two electrons can have the same values of all the four quantum numbers. This is called

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

Answer 1

The Correct Option is D

The question asks which principle states that no two electrons in a given atom can have the same values for all four quantum numbers. Let's evaluate the provided options to determine the correct principle:

1. Hund's Rule: Hund's Rule is related to the distribution of electrons among orbitals of the same energy. It suggests that electrons will occupy degenerate orbitals singly before pairing up to minimize electron repulsion. This rule does not relate to the prohibition of identical quantum numbers.
2. Aufbau Principle: The Aufbau Principle dictates the order in which electrons fill orbitals. Electrons occupy the lowest energy orbital available. Again, this principle does not address the unique set of quantum numbers for electrons.
3. Uncertainty Principle: This principle, formulated by Heisenberg, is a fundamental theory in quantum mechanics that states it is impossible to simultaneously know the exact position and momentum of a particle. It does not pertain to electron quantum numbers.
4. Pauli Exclusion Principle: Proposed by Wolfgang Pauli, this principle states that no two electrons in the same atom can have an identical set of values for all four quantum numbers. This exclusivity ensures each electron in an atom has a distinct quantum state.

Given the explanations of these concepts, the correct answer is the Pauli Exclusion Principle. This principle ensures that within a single atom, all electrons have a unique set of quantum numbers (n, l, m_l, m_s), thereby maintaining distinct electron identities.

Thus, the correct answer is Pauli Exclusion Principle.