Which of the following statements about transition metals is incorrect?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Most transition metals are ‘noble’, that is, they are unaffected by single acids.
Option (1) The colour of hydrated transition metal ions is due to d–d transitions of electrons. — Correct about transition metals. Water ligands split the d orbitals, and absorbing visible light moves an electron from a lower to a higher d orbital; the ion shows the complementary colour.
Option (2) Most transition metals are ‘noble’, that is, they are unaffected by single acids. — Incorrect about transition metals.
Many transition metals are electropositive enough to dissolve in mineral acids and only a few are noble, so “most” is wrong.
Of the first series, every metal except copper is oxidised by 1 M H+.
Option (3) The complex formation of transition metal ions is often accompanied by a change of colour. — Correct about transition metals. A new ligand changes the d-orbital splitting and so the colour: green [Ni(H2O)6]2+ turns pale blue when ethane-1,2-diamine is added.
Option (4) The compounds of transition metals in low oxidation states are generally ionic. — Correct about transition metals. Ionic character decreases as the oxidation number rises; the MO oxides are ionic, while Mn2O7 is a covalent green oil.
NCERT (2026-27 edition):
4.3.8 Chemical Reactivity and E° Values – “Transition metals vary widely in their chemical reactivity. Many of them are sufficiently electropositive to dissolve in mineral acids, although a few are ‘noble’—that is, they are unaffected by single acids.”