Question

Statement 1 : Two electrons in the 2s sub-shell must have opposite spins.
Statement 2 : The Pauli exclusion principle states that no two electrons in the same atom can have identical quantum numbers.

• A. Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.
• B. Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.
• C. Statement 1 is correct but Statement 2 is not correct.
• D. Statement 1 is not correct but Statement 2 is correct.
• E. Both the Statement 1 and Statement 2 are not correct.

Answer 1

The correct option is A

Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.
The Pauli exclusion principle is the quantum mechanical principle that states that two identical fermions (particles with half-integer spin) cannot occupy the same quantum state simultaneously. In the case of electrons, it can be stated as follows: it is impossible for two electrons of a poly-electron atom to have the same values of the four quantum numbers: n, the principal quantum number, $l$ , the angular momentum quantum number, $m_l$, the magnetic quantum number, and $m_s$, the spin quantum number. For example, if two electrons reside in the same orbital, and if their n, $l$, and $m_l$ values are the same, then their $m_s$ must be different, and thus the electrons must have opposite half-integer spins of $1/2$ and $-1/2$.