Electronic configuration of the given transition metal ions are : Sc3(Z=21)ls22s22p63s23p6 Ti2+(Z=22)1s22s22p63s23p63d2 Ti3+(Z=22)1s22s22p63s23p63d1 V2+(Z=23)1s22s22p63s23p63d3 Since, magnetic moment is directly proportional to the number of unpaired electrons. The correct increasing order of magnetic moment is Sc3+<Ti3+<Ti2+<V2+ because they have 0,1,2 and 3 unpaired electrons respectively.