Which of the following ions show higher spin only magnetic moment value?
Mn2+ (3d5) and Fe2+(3d6) have more number of unpaired electrons 5 and 4 than Ti3+(3d1) and Co3+(3d7) which have only 1 and 3 unpaired electrons.
Magnetic moment = 
Where n is the number of unpaired electrons.
Magnetic moment for all elements:
Mn2+ = 
=5.91
Fe2+=
=2.89
Ti3+=
=1.73
Co3+=
=3.87
Greater the value of n, greater the magnetic moment.
So, Mn2+ has the highest magnetic moment
1