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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 2 · Set 3 · Q24
(a) E_( Mn^2+ / Mn )^° is -1.18 V. Why is this value highly negative in comparison to neighbouring d-block elements? (b) What is lanthanoid…
(a)
$\displaystyle \mathrm{E}_{\left(\mathrm{Mn}^{2+} / \mathrm{Mn}\right)}^{\circ}$ is -$\displaystyle 1.18$ V. Why is this value highly negative in comparison to neighbouring d-block elements ?
(b)
What is lanthanoid contraction ?
(c)
Zn, Cd and Hg are soft metals. Why ?
Marking-scheme solution
(a)
Mn2+ results in the half-filled (d5) configuration which has extra stability.
(b)
The steady decrease in atomic and ionic radii in lanthanoid series.
(c)
Due to weak interatomic interactions / weak metallic bonds.
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