Which of the following properties are shown by d-block elements?
A. Complex formation
B. Chelating agents
C. Bleaching agents
D. Catalytic agents
E. Alloy formation
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A, D, E only
The characteristic properties of transition elements come from their partly filled d orbitals: variable oxidation states, coloured ions, complex formation, catalytic activity, paramagnetism and alloy formation.
(A) Complex formation — True. Small, highly charged ions with vacant d orbitals bind many ligands, so transition metals form a large number of complexes.
(B) Chelating agents — False. Chelating agents are polydentate ligands (en, EDTA, oxalate) that bind a metal ion; they are not a property shown by the d-block elements themselves.
(C) Bleaching agents — False. Bleaching is not a characteristic property of d-block elements; common bleaching agents are compounds such as chlorine, bleaching powder and \( \ce{SO2} \).
(D) Catalytic agents — True. Their variable oxidation states and ability to form complexes make transition metals and their compounds good catalysts (\( \ce{V2O5} \) in the Contact process, Fe in the Haber process, Ni in hydrogenation).
(E) Alloy formation — True. Transition metals have similar atomic radii, so they readily form alloys such as steels, brass and bronze.
NCERT (2026-27 edition):
Electronic Configurations of the d-Block Elements – “… The d orbitals of the transition elements protrude to the periphery of an atom more than the other orbitals (i.e., s and p), hence, they are more influenced by the surroundings as well as affect the atoms or molecules surrounding them. In some respects, ions of a given dn configuration (n = 1 – 9) have similar magnetic and electronic properties. 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 also exhibit catalytic property and paramagnetic behaviour.”
Alloy Formation – “An alloy is a blend of metals prepared by mixing the components. Alloys may be homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other. Such alloys are formed by atoms with metallic radii that are within about 15 percent of each other. Because of similar radii and other characteristics of transition metals, alloys are readily formed by these metals.”