In the Stern-Gerlach effect, observed when a
beam of atoms is passed through an inhomogeneous
magnetic field, which of the following is true?
(A) The atoms must be ionized first.
(B) No deflection is observed for hydrogen atoms.
(C) Only one deflection is observed for hydrogen
(D) Two distinct deflections are observed for sodium
(Z = 11) atoms.
(E) Three distinct deflections are observed for
magnesium (Z = 12) atoms.
I know E is right, but I don't understand why D is not.
Could anyone explain this to me? Thanks in advance!