The correct statement about \(d-\)block elements is
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → V2O5 is amphoteric in nature
The acidic character of transition metal oxides rises with the oxidation state of the metal: low oxidation state oxides are basic, the highest ones (such as \( \ce{Mn2O7} \), \( \ce{CrO3} \)) are acidic, and those in between are amphoteric. Vanadium is +5 in \( \ce{V2O5} \); the oxide is amphoteric though mainly acidic. It reacts with alkalis as well as acids:
\( \ce{V2O5 + 6NaOH -> 2Na3VO4 + 3H2O} \)
\( \ce{V2O5 + 2HCl -> 2VO2Cl + H2O} \)
Why the other options are incorrect
Option (2) Ziegler catalyst consists of Al(CH3)3 and ZrCl4 — Incorrect. The Ziegler catalyst is TiCl4 with \( \ce{Al(CH3)3} \) (or another trialkylaluminium), used to make polyethylene.
Option (3) Cu+ ions do not show disproportionation reaction — Incorrect. \( \ce{Cu^{+}} \) is unstable in water and does disproportionate, because the high hydration enthalpy of \( \ce{Cu^{2+}} \) more than makes up for the second ionisation enthalpy of copper.
\( \ce{2Cu+ (aq) -> Cu^{2+} (aq) + Cu (s)} \)
Option (4) MnF7 is more stable than Mn2O7 — Incorrect. \( \ce{MnF7} \) does not exist; the highest fluoride of manganese is MnF4. Oxygen can form multiple bonds to the metal, so Mn reaches +7 only in the oxide, \( \ce{Mn2O7} \).
NCERT (2026-27 edition):
Oxides and Oxoanions of Metals – …
