Question

Assertion: Spin quantum number can have the value $ +{\scriptstyle{}^{1}/{}_{2}} $ or $ -{\scriptstyle{}^{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.