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.......
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → +5, +6, +4
A transition metal can use both its 4s and its 3d electrons in bonding. From Sc to Mn the highest oxidation state equals the total number of 4s and 3d electrons (the group number). After Mn the d electrons begin to pair up and are held more firmly by the rising nuclear charge, so the highest oxidation state falls again, and the higher states of these elements are rare.
V (Z = 23): \( \mathrm{[Ar]\,3d^{3}\,4s^{2}} \), five electrons in all, so the highest state is +5, as in \( \ce{V2O5} \) and \( \ce{VO4^3-} \).
Fe (Z = 26): \( \mathrm{[Ar]\,3d^{6}\,4s^{2}} \). Its common states are +2 and +3, but in the ferrate ion \( \ce{FeO4^2-} \) iron is in the +6 state: \( x + 4(-2) = -2 \Rightarrow x = +6 \).
Ni (Z = 28): \( \mathrm{[Ar]\,3d^{8}\,4s^{2}} \); highest state +4 (common state +2).
So the highest oxidation states of V, Fe and Ni are +5, +6 and +4.
NCERT (2026-27 edition):
Oxidation States
