Use Hund's rule to derive the electronic configuration of `Ce^(3+)` ion, and calculatel its magntic moment on the basis of spin-only formula.

Explanation

`._(58)Ce= [Xe]^(54) 4f^(1) 5d^(1) 6s^(2)`
`Ce^(3+) = [Xe]^(54) 4f^(1) , i.e., `there is only one unpaired electron , i.e., `n=1`. Hence,
`mu = sqrt(n(n+2)) BM = sqrt(1( 1+2)) = sqrt( 3) BM= 1.73BM`