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Chemistry · 2024 · 2 marks
CBSE 2024 · Region 2 · Set 1 · Q19
(a) What is lanthanoid contraction? Actinoid contraction is greater from element to element than lanthanoid contraction. Why?
(a)
What is lanthanoid contraction ? Actinoid contraction is greater from element to element than lanthanoid contraction. Why ?
OR
(b)
Why do transition metals have high enthalpy of atomization ? Which element of 3d-series has lowest enthalpy of atomization ?
Marking-scheme solution
The steady decrease in atomic or ionic radii with increase in atomic number due to poor shielding effect of 4f subshell.
Because shielding effect of $\displaystyle 5$ f subshell is poorer as compared to that of 4f subshell.
All The d-and f-Block Elements questions2024 question paperNCERT solutions: The d-and f-Block ElementsPractice The d-and f-Block Elements →
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CBSE Class 12 Chemistry past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.