Magnetic moment (µ) is given asµ=√n(n+2) where, n is number of unpaired electrons. Fe2+:[Ar]3d6; number of unpaired electrons =4 Ti2+:[Ar]3d2; number of unpaired electrons =2 Cu2+:[Ar]3d9; number of unpaired electrons =1 V2+:[Ar]3d3; number of unpaired electrons =3 Hence, the increasing order of magnetic moment is as Cu2+<Ti2+<V2+<Fe2+