CBSE 2022 · Region 5 · Set 3 · Q8 · 3 marks
Give reasons for the following statements :(a)Transition elements and their compounds act as good catalysts.(b)$\displaystyle \mathrm{E}^{\mathrm{o}}\left(\mathrm{Mn}^{2+} / \mathrm{Mn}\right)$ value is highly negative as compared to other elements.(c)$\displaystyle \mathrm{Cr}^{2+}$ is a strong reducing agent.
Give reasons for the following statements :
(a)
Transition elements and their compounds act as good catalysts.
(b)
$\displaystyle \mathrm{E}^{\mathrm{o}}\left(\mathrm{Mn}^{2+} / \mathrm{Mn}\right)$ value is highly negative as compared to other elements.
(c)
$\displaystyle \mathrm{Cr}^{2+}$ is a strong reducing agent.
Marking-scheme solution
(a) Variable or multiple oxidation state / ability to form complexes / they provide large surface area for adsorption (utilises (n-$\displaystyle 1$) d and ns electrons for bonding).
(b) \(\displaystyle \mathrm{3d}^{5}\) or half-filled stable configuration in \(\displaystyle \mathrm{Mn}^{2+}\).
(c) because it changes to more stable +$\displaystyle 3$ oxidation state having \(\displaystyle \mathrm{t}_{2 \mathrm{~g}}{ }^{3}\) configuration.
The d-and f-Block ElementsGeneral Properties of the Transition Elements (d-Block)Understandshort_answermedium
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CBSE Class 12 Chemistry past-paper question from the 2022board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.