Explanation:
\({\mathrm{\mu=\sqrt{\mathrm{n}(\mathrm{n}+2)}=3.86 \mathrm{BM}}}\)
On solving, \({\mathrm{\mathrm{n}=3}}\)
\(\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\rm{[n = No}}{\rm{.of}}\,{\rm{unpaired}}\,{\rm{electrons]}}\)
Electronic configuration of ion in +2 oxidation state should be \({\mathrm{[\mathrm{Ar}] 3 \mathrm{~d}^{3}}}\).
Thus electronic configuration of atom will be \({\mathrm{[\mathrm{Ar}] 3 \mathrm{~d}^{3} 4 \mathrm{~s}^{2}}}\) (Vanadium).
\({\mathrm{\therefore}}\) Atomic number of the metal is 23 .So, the correct option is (2).