All transition elements are d-block elements, but all d-block elements are not transition elements.
Explain.
Elements in which the last electron enters in the (^-orbitals, are called <7-block elements or transition elements. These elements have the general outer electronic configuration (n-1)${{d}^{1-10}}$ n${{s}^{0-2}}$.
Zn, Cd and Hg having the electronic configuration, (n — l)${{d}^{10}}$ n${{s}^{2}}$ do not show most of the properties of transition elements. The d-orbitals in these elements are completely filled in the ground state as well as in their common oxidation states.
Therefore, they are not regarded as transition elements. Thus, on the basis of properties, all transition elements are d-block elements but on the basis of electronic configuration, all d-block elements are not transition elements.