Read the passage carefully and answer the following questions.

There are mainly four series of the transition metals, 3d series (Sc to Zn), 4d series (Y to Cd), 5d series (La and Hf to Hg) and 6d series which has Ac and elements from Rf to Cn. The two series of the inner transition metals; 4f (Ce to Lu) and 5f (Th to Lr) are known as lanthanoids and actinoids respectively. Their chemical properties are transitional between those of s and p-block elements. The transition metals (with the exception of Zn, Cd and Hg) are very hard and have low volatility. Their melting and boiling points are high. Transition metals have incomplete d subshell either in neutral atom or in their ions. With partly filled d orbitals these elements exhibit certain characteristic properties such as display of a variety of oxidation states, formation of coloured ions and entering into complex formation with a variety of ligands. The transition metals and their compounds are known for their catalytic activity.

The highest oxidation states shown by V, Fe and Ni respectively are.......

+5, +6, +4

The correct answer is Option (2) → +5, +6, +4

In the 3d transition series, the highest oxidation state an element can exhibit is generally determined by the sum of its $4s$ and unpaired $3d$ electrons. As we move across the series, the stability and commonality of these high states vary.

Analysis of the Elements

• Vanadium (V): Its electronic configuration is $[Ar] 3d^3 4s^2$. By losing or sharing all five of its valence electrons, it reaches its maximum oxidation state of +5 (commonly seen in $V_2O_5$ or $VO_4^{3-}$).
• Iron (Fe): Its electronic configuration is $[Ar] 3d^6 4s^2$. While +2 and +3 are the most common states, Iron can reach a maximum oxidation state of +6 in specific highly oxidizing conditions, such as in the ferrate ion ($FeO_4^{2-}$).
• Nickel (Ni): Its electronic configuration is $[Ar] 3d^8 4s^2$. While +2 is by far the most dominant state, Nickel can exhibit a maximum oxidation state of +4 in certain complex compounds and oxides (like $K_2NiF_6$ or $NiO_2$).