Question

Assertion: Spin quantum number can have the value $+{}^1/{}_2$ or $-{}^1/{}_2$ . Reason: (+) sign here signifies the wave function.

• A. both assertion and reason are correct and reason is the correct explanation of assertion
• B. both assertion and reason are correct and reason is the not correct explanation of assertion
• C. assertion is true but reason is false
• D. both assertion and reason are false

Answer 1

Answer: (C)

: Spin angular momentum of the electron, a vector quantity, can have two orientations (represented by $+$ and $-$ sign) relative to a chosen axis. These two orientation are distinguished by the spin quantum number $m_s$ equals to $+1/2$ or $-1/2$ . These are called the two spin states of the electron and are normally represented by the two arrows $\uparrow$ (spin up) and $\downarrow$ (spin down) respectively.