• # question_answer Direction: The dissociation of complex may be expressed as ${{[M{{L}_{x}}]}^{4+}}\,+xL$ and equilibrium constant of this is known as instability constant which is a measure of stability. The stability of complex depends on EAN of central atom, charge on metalion, basic nature of ligand and chelation. The EAN of $Co$ in $Co{{(CO)}_{4}}$ is 35 and it is less stable. It attains stability by A) oxidation of Co            B) reduction of Co   C) dimerization                 D) tetramerization

$C{{O}_{2}}\,{{(CO)}_{8}}$ is most stable. Thus, $CO\,{{(CO)}_{4}}$ attains stability by dimerisation.