Answer
(a) \[[Ar]3{{d}^{3}}4{{s}^{2}}\]
(b) \[[Xe]4{{f}^{14}}5{{d}^{5}}6{{s}^{2}}.\]
(c) \[[Kr]4{{d}^{10}}.\]
Work Step by Step
The transition elements have the unique properties to exhibit variable valencies ranging from \[~0\text{ }to\text{ +7}.\] This unique characteristic of transition elements is due to the availability of vacant d orbitals in transition metals.
(a) Ground state electron configuration of vanadium is \[[Ar]3{{d}^{3}}4{{s}^{2}}.\] Hence, the highest possible oxidation state is obtained by the loss of all s and d electrons. So, maximum oxidation state for \[V\text{ }is\text{ }+5\].
(b) The ground state electron configuration of rhenium is \[[Xe]4{{f}^{14}}5{{d}^{5}}6{{s}^{2}}.\] Hence, the highest possible oxidation state for Re would \[be\text{ +7}\], which can be acquired by the loss of five electrons from the 5d orbital and two electrons from the 6s orbital.
(c) The ground state electron configuration of palladium is \[[Kr]4{{d}^{10}}.\] It can lose a maximum of four electrons to obtain the highest oxidation state of +4.
