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🧪 Chemistry  ·  d- and f-Block Elements  ·  NEET & JEE

Which transition metal is used in the Contact process as a catalyst?

Answer: Vanadium(V) oxide (V2O5).

  • A Vanadium(V) oxide (V2O5)
  • B Iron, the catalyst used instead in the Haber process for ammonia
  • C Platinum, the catalyst used instead in the Ostwald process for nitric acid
  • D Nickel, the catalyst used instead in the hydrogenation of vegetable oils

Correct answer: A. Vanadium(V) oxide (V2O5)

Explanation: V2O5 catalyses the oxidation of SO2 to SO3 in the Contact process for H2SO4 manufacture.

Colours of Common Transition Metal Ions (Aqueous)Cu²⁺ blueFe²⁺ pale greenFe³⁺ brown-yellowMn²⁺ pale pinkNi²⁺/Cr³⁺ greenColour arises from d-d electron transitions - d⁰ ions like Sc³⁺, Ti⁴⁺ are colourless

Aqueous solutions of transition metal ions show characteristic colours caused by electrons absorbing visible light to jump between split d-orbitals; the exact colour depends on the metal, its oxidation state, and surrounding ligands.

Concept context

Transition metals (d-block) and lanthanides/actinides (f-block). Known for coloured compounds, variable oxidation states, complex formation, and catalytic properties. Frequently tested in JEE and NEET.

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