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Chemistry · 2025 · 3 marks
The d-and f-Block ElementsGeneral Properties of the Transition Elements (d-Block)3 marksUnderstandshort answer
CBSE 2025 · Region 4 · Set 2 · Q26
Give explanation for each of the following observations: (a) With the same d-orbital configuration ( d^4), Mn^3+ ion is an oxidising agent whereas…
Give explanation for each of the following observations :
(a)
With the same d-orbital configuration $\displaystyle \left(\mathrm{d}^{4}\right), \mathrm{Mn}^{3+}$ ion is an oxidising agent whereas $\displaystyle \mathrm{Cr}^{2+}$ ion is a reducing agent.
(b)
Actinoid contraction is greater from element to element than that among lanthanoids.
(c)
Transition metals form large number of interstitial compounds with H, B, C and N.
Marking-scheme solution
(a)
Change from Mn3+ to Mn2+ results in extra stable half filled d5 configuration.
Cr2+ is reducing as its configuration changes from d4 to d3 which is stable half filled t2g3
configuration.
(b)
Due to poorer shielding offered by 5f electrons than 4f.
(c)
H, B, C and N atoms being small in size get trapped inside the crystal lattices of transition
metals.
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