Magnetic moment of a divalent ion in aqueous solution of an element with  atomic number 25 is :

5.92 BM

The compound with atomic number 25 is Manganese, its electronic configuration is:

The electronic configuration in the +2 oxidation state is

Number of unpaired electrons = 5

So, magnetic moment, \(\mu = \sqrt{n(n + 2)}\)

                                  \(\mu = \sqrt{5( 5 + 2)}\)

                                   \(\mu = \sqrt{35}\)

                                   \(\mu = 5.92\) BM