CBSE 2022 · Region 3 · Set 1 · Q4 · 3 marks
Account for the following :(i)$\displaystyle \mathrm{Cu}^{2+}$ salts are coloured while $\displaystyle \mathrm{Zn}^{2+}$ salts are white.(ii)$\displaystyle \mathrm{E}^{\circ}$ value for the $\displaystyle \mathrm{Mn}^{3+} / \mathrm{Mn}^{2+}$ couple is much more positive than that for $\displaystyle \mathrm{Cr}^{3+} / \mathrm{Cr}^{2+}$.(iii)Transition metals form alloys.
Account for the following :
(i)
$\displaystyle \mathrm{Cu}^{2+}$ salts are coloured while $\displaystyle \mathrm{Zn}^{2+}$ salts are white.
(ii)
$\displaystyle \mathrm{E}^{\circ}$ value for the $\displaystyle \mathrm{Mn}^{3+} / \mathrm{Mn}^{2+}$ couple is much more positive than that for $\displaystyle \mathrm{Cr}^{3+} / \mathrm{Cr}^{2+}$.
(iii)
Transition metals form alloys.
Marking-scheme solution
(i) Because \(\displaystyle \mathrm{Cu}^{2+}\) has one unpaired electron in 3d-orbital whereas \(\displaystyle \mathrm{Zn}^{2+}\) has no unpaired electron \(\displaystyle / \mathrm{Cu}^{2+}\) shows d-d transition whereas \(\displaystyle \mathrm{Zn}^{2+}\) does not.
(ii) Because Mn is more stable in +$\displaystyle 2$ due to stable \(\displaystyle 3 d^{5}\) configuration whereas Cr is more stable in +$\displaystyle 3$ due to stable \(\displaystyle t_{2 g}^{3}\) configuration / Much larger third ionization energy of Mn as compared to Cr.
(iii) Because of similar atomic radii.
The d-and f-Block ElementsGeneral Properties of the Transition Elements (d-Block)Understandshort_answermedium
More from The d-and f-Block Elements
- (i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a…2022 · asked 3×
- (i) Describe giving reason which one of the following pairs has the property indicated: (I) Fe or Cu - higher…2026 · asked 3×
- The diamagnetic species is:2025 · asked 3×
- Assertion: Zr and Hf are of almost similar atomic radii. Reason (R): This is due to Lanthanoid contraction.2024 · asked 3×
- (i) When pyrolusite ore is fused with KOH, in presence of air, a dark green coloured product 'A' is obtained…2025 · asked 3×
- The element having [Ar] 3 d^10 4 s^1 electronic configuration is2025 · asked 3×
- From the given E^ values of the first row transition elements, answer the following questions: (i) Why is E…2022 · asked 3×
- Account for the following: (i) Transition metals and their compounds show catalytic activities. (ii) Zn, Cd…2022 · asked 3×
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.