Paramagnetic property depends upon the number of unpaired electrons. Higher the number of unpaired electrons, higher the paramagnetic property will be. Cu2+=[Ar]3d9, no. of unpaired electrons =1 V2+=[Ar]3d3, no. of unpaired electrons =3 Cr2+=[Ar]3d4, no. of unpaired electrons =4 Mn2+=[Ar]3d5, no. of unpaired electrons =5 Hence, correct order is Cu2+<V2+<Cr2+<Mn2+