Value of magnetic moment depends upon number of unpaired electrons.
All given metal ions (except $Ti ^{3+}\left(3 d ^{1}\right)$ ) have either fully filled d-subshell $\left( Zn ^{2+}, Cu ^{+}\right)$or empty d-subshell $\left( Sc ^{3+}\right)$.
As such only $Ti ^{3+}$ has a net value of magnetic moment.
Magnetic moment of $Ti ^{3+}=\sqrt{ n ( n +2)} BM $
$=\sqrt{1(1+2)} BM $
$=\sqrt{3} BM $
$=1.73\, BM$.