The catalytic activity of transition metals and their compounds is ascribed mainly to

The catalytic activity of transition metals and their compounds is ascribed mainly to
  1. their magnetic behaviour
  2. their unfilled $d$-orbitals
  3. their ability to adopt variable oxidation states
  4. their chemical reactivity

Solution

Transition metals show variable oxidation states, due to which they can perform as catalyst. $\begin{aligned} & \text {e.g., } 2 \mathrm{SO}_2+\mathrm{O}_2 \underset{\text { (catalyst) }}{\stackrel{\mathrm{V}_2 \mathrm{O}_5}{\longrightarrow}} 2 \mathrm{SO}_3 \\ & \mathrm{SO}_2+\stackrel{+5}{\mathrm{~V}_2} \mathrm{O}_5 \longrightarrow \mathrm{SO}_3+\stackrel{+4}{\mathrm{~V}_2} \mathrm{O}_4 \\ & \stackrel{+4}{\mathrm{~V}_2} \mathrm{O}_4+\mathrm{O}_2 \longrightarrow \stackrel{+5}{\mathrm{~V}_2} \mathrm{~O}_5 \\ & \end{aligned}$

Asked in: NEET 2012 (Mains)

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