The species that possesses unpaired electron shows paramagnetic behaviour. The electronic configuration of given element is written as, Cu2+(27)→1s22s22p63s23p63d9→1 unpaired e− Cr2+(22)→1s22s22p63s23p63d4→4 unpaired e− V2+(23)→1s22s22p63s23p63d34s2→3 unpaired e− Mn2+(23)→1s22s22p63s23p64d03d5→5 unpaired e− This implies that the correct order of increasing paramagnetic behaviour of ions is, Cu2+ < V2+ < Cr2+ < Mn2+
