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Statement-1: 4d&5d series element have...

Statement-1:
`4d&5d` series element have nearly same atomic radius.
Statament-2: Lanthanoide contraction.

A

Statement-1 is true , Statement-2 is true and Statement-2 is correct explanation for Statement-1

B

Statement-1 is true, Statement-2 is True and Statement-2 is Not correct explanation for statement-1

C

Statement-1 is true, Statement-2 is False

D

Statement-1 is False, Statement-2 is True

Text Solution

Verified by Experts

The correct Answer is:
A
The atomic radii of the second `(4d series )` and third , `(5d series)` transition series are almost the same. This phenomenon is associated with the intervention of the `4f` orbital which must be filled before the `5d` series of elements begin . The filling of `4f` before `5d` orbital results in a regular decrease in atomic radii called Lanthanoid contraction which essentially compensates for the expected increase in atomic size with increasing atomic number . The net result of the lanthanoid contraction is that the second and the third d series exhibit similar radii (e.g., Zr 160 pm, Hf 159 pm).
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