Account of the following.
(i) The enthalpy of atomisation is lowest for Zn in `3d`-series of the transition elements.
(ii) Identify the metal in `MO_(3)F` and justify your answer.
(iii) Transition metals form a large number of complexes.
(iv) `d^(1)` configuration is very unstable in ions.

Explanation

(i) Zinc has completely filled d-orbitals, which limits its rendency to form metallic bonds. Thus, it requires least enthalpy to get atomised.
(ii) `MO_(3)F` is `MnO_(3)F`.
In `MO_(3)F`.
`x+3xx(-2)+(-1)=0`
or, `x=+7`, i.e. M is in oxidation state of `+7`. Hence, the given compound is `MnO_(3)F`.
(iii) Due to the comparatively smaller size of the metal ions, their high jonic charges and the availibility of vacant d-orbitals for bond formation, transition metals form a large number of complex compounds.
(iv) Ions of transition metals with `d^(1)` configuration tend to lose one electron to acquire `d^(0)` configuration that is quite stabl. oxidation or disproportion reaction hence unstable.