the value of the spin only moment for one of the following configurations is 2.84 b.m the correct one isa. d5{in strong ligand field}b.d3 {in weak as well asin strong ligand field}c.d4{in weak ligand field}d. d4 {in strong ligand field}

magnetic moment is given by the formula,spin only magnetic moment=sqrt n(n+2)
where n is the number of unpaired electron
the answer will be d4 in astrong field ligand
ex-Mn(CN)6 ^3-
no of 3d electron=4
no of unpaired electron=2
therefore spin only magnetic moment=sqrt(2(4))=2.82