Q.8. Find the sum of minimum and maximum possible value of x in $F{e}^{+x}$ ion, if magnetic moment of $F{e}^{+x}$ = 4.89 B. M.

Calculate the magnetic moments of Fe2+ and Fe3+

Solution: In Fe2+ there are 4 unpaired electrons.

μ = √4(4+2) = √24 = 4.89 B.M
 

In Fe3+ there are 5 unpaired electrons.

μ = √5(5+2) = √35 = 5.91 B.M

Therefore  magnetic moment is given  4.89
so in Fe there should be 4 unpaired electron 
it will be possible only in 0 and +2 oxidation state,
therefore , the sum of minimum and maximum possible  values of x = 2
Regards