What is the atomicity of the following : ozone

Explanation

(i) Because the presence of vacant (n - 1) d orbitals, which one can accept one or more electron pairs from ligands.
(ii) High charge density on transition metal cations :
For example : `[Co(H_2O)_4]^(2+), [Cu(NH_3)_4]^(2+)` etc.