Fi say that an electron is a spin-1/2 particle, which of the following statement(s) is/are true?
a) the magnitude of the spin vector is 1/2
b) the magnitude of the spin vector is hbar/2
c) the magnitude of the spin vector along some axis is 1/2
d) the magnitude of the spin vector along some axis is hbar/2

d) The magnitude of the spin vector along some axis is hbar/2

Explanation:

The magnitude of the spin vector is defined by the following equation:

where s = n / 2 is the spin quantum number and n can only take positive integer values. For the electron we have and

On the other hand, the magnitude of S along some axis is given by:  

with i=x,y,z. So, in this case we have:

increases it